[#883, !506] clean up code

[#883, !506] updated unit tests

[#883, !506] addressed comments - using smart pointer for WorkItem and using queue container as template argument

[#883, !506] moved thread pool in util lib

[#883, !506] changed thread pool interface

[#883, !506] fixed rebase

[#883, !506] updated copyrights

[#883, !506] fixed rebase

[#883, !506] fixed rebase

[#883, !506] use nullptr for empty task

[#883, !506] use references instead of objects whenever possible

[#883, !506] fixed typo

[#883, !506] fixed comments

[#883, !506] fixed comments

[#883, !506] fixed typos

[#883, !506] fixed typo

[#883, !506] fixed typo

[#883, !506] updated unit tests

[#883, !506] updated thread pool unit tests

[#883, !506] added thread pool unit tests

[#883, !506] added LockGuard unit tests

[#883, !506] added doxigen and cleaned up code

changed log messages

use std::lock_guard whenever possible

added lock guard

[#883, !506] added thread pool

[#964,!577] Two trivial fixes as a result of second review.

- Addeed asterisk in the changelog to mark it incompatible change.
- Fixed comma character in the new line.

[#964,!577] Fixed segfaulting unit test

src/lib/http/client.cc
    HttpClient::CloseIfOutOfBandwith() - added missing loop
    break after erasure.

[#964,!577] Added unit tests

src/lib/dhcp/tests/iface_mgr_unittest.cc
    Modified tests to verify that external socket callbacks receive
    the correct socket descriptor when invoked by IfaceMgr.

src/lib/http/tests/server_client_unittests.cc
    TEST_F(HttpClientTest, closeIfOutOfBandwidth) - new test to
    verifies HttpClient::closeIfOutOfBandwidth()

[#964,!577] Revamped to detect and close OOB Connections

Rather than just unregistering the socket, we now actually close
the Connection. This ensures we never end up with an unregistered
but open connection.

src/hooks/dhcp/high_availability/ha_service.*
    HAService::clientConnectHandler() - modified to call
    HttpClient::closeIfOutOfBandwidth().

src/lib/http/client.*
    Connection - replaced isTransaction(int socket_fd) with
    isMySocket(int socket_fd)

    ConnectionPool - replaced isTransaction(int socket_fd) with
    closeIfOutOfBandwidth(int socket_fd)

    HttpClient - replaced isTransaction(int socket_fd) with
    closeIfOutOfBandwidth(int socket_fd)

[#964,!577] Added external socket ready handler to HAService

src/hooks/dhcp/high_availability/ha_service.*
    HAService::socketReadyHandler(int tcp_native_fd) - new handler for external socket ready
    callback. It detects out-of-transaction ready socket and unregisters it.

src/lib/http/client.*
    isTransactionOngoing(int socket_fd) - new method to return true if any of the clients
    connections are using the socket in an ongoing transaction

[#964,!577] Added socket descriptor parameter to IfaceMgr external callback handler

src/lib/dhcp/iface_mgr.*
    typedef SocketCallback - added socket descriptpor parameter
    Added socket fd to invocations of socket ready callback

src/bin/dhcp4/dhcp4to6_ipc.*
    void Dhcp4to6Ipc::handler(int /* fd */)

src/bin/dhcp6/dhcp6to4_ipc.*
    void Dhcp6to4Ipc::handler(int /* fd */)

     Dhcp6to4Ipc& ipc = Dhcp6to4Ipc::instance();
     Pkt6Ptr pkt;

src/hooks/dhcp/high_availability/ha_service.*
    socketReadyHandler() - initial stub implementation of socket ready handler

[970-implement-multi-threading-critical-section] Removed the enabled_ local copy of the MT mode

[970-implement-multi-threading-critical-section] Moved to Camel names

[970-implement-multi-threading-critical-section] Finished first version

[970-implement-multi-threading-critical-section] First version

[#989] updated version and fixed some typos

[#974] slightly changed documentation about netconf

Merge branch '974-1-7-1-release' of https://gitlab.isc.org/isc-projects/kea into 974-1-7-1-release

[#974] parsers regenerated for 1.7.1

[#974] copy right dates, mes files Changelog prepared for release

[#971] copy right dates, mes files Changelog prepared for release

[#971] bumped up lib versions for 1.7.1

[fix-904-2] Fixed rebase failures

[fix-904] Removed extra argument

[904-add-ability-to-force-a-cb-update-remotely] Fixed typo

[904-add-ability-to-force-a-cb-update-remotely] Updated Changelog entry

[904-add-ability-to-force-a-cb-update-remotely] Used "on demand" instead of pull at the exception of the command name

[904-add-ability-to-force-a-cb-update-remotely] Added ChangeLog entry for config-backend-pull

[904-add-ability-to-force-a-cb-update-remotely] Addressed last comments

[904-add-ability-to-force-a-cb-update-remotely] Addressed comments for the v4 part

[904-add-ability-to-force-a-cb-update-remotely] Addressed comments but still command to update

[904-add-ability-to-force-a-cb-update-remotely] Added server-update command

[#752] AUTHORS, ChangeLog updated.

[#752] Updated alloc_engine_messages.mes

Add log message containing classes during allocation failure

[965-fix-doxygen-warnings] Fixed trivial doxygen warnings

[393-global-search-through-leases-by-mac-or-hostname-w-o-specifying-a-subnet-id] Added ChangeLog entry for leases by hostname and co (2)

[393-global-search-through-leases-by-mac-or-hostname-w-o-specifying-a-subnet-id] Added ChangeLog entry for leases by hostname and co

[393-global-search-through-leases-by-mac-or-hostname-w-o-specifying-a-subnet-id] Addressed comments

[393-global-search-through-leases-by-mac-or-hostname-w-o-specifying-a-subnet-id] Added unit tests for new commands

[393-global-search-through-leases-by-mac-or-hostname-w-o-specifying-a-subnet-id] Added new command docs

[393-global-search-through-leases-by-mac-or-hostname-w-o-specifying-a-subnet-id] Implemented new commands

[393-global-search-through-leases-by-mac-or-hostname-w-o-specifying-a-subnet-id] Added get leases 4 and 4 by hostname to the API

[393-global-search-through-leases-by-mac-or-hostname-w-o-specifying-a-subnet-id] Moves lease hostnames to lower case

[869] ChangeLog updated.

[869-add-ability-to-retrieve-configure-command-line-from-binaries] Moved configure arguments block

[869-add-ability-to-retrieve-configure-command-line-from-binaries] Added configure arguments to config.report

[#795] ChangeLog updated.

[#795] unit tests tweaked for new configuration

[#795] sockets paths unified between examples and default configs

[remove-unused-variable-20191025-2] [fix2] Removed unused variables

[remove-unused-variable-20191025] [fix] Removed unused variables

[219-allow-an-option-value-to-be-set-from-an-expression] Added ChangeLog for options from expressions

[219-allow-an-option-value-to-be-set-from-an-expression] Addressed comments

[219-allow-an-option-value-to-be-set-from-an-expression] Added new tests and an example

[219-allow-an-option-value-to-be-set-from-an-expression] Checkout: adding call tests

[219-allow-an-option-value-to-be-set-from-an-expression] Added docs

[219-allow-an-option-value-to-be-set-from-an-expression] Checkpoint: code and test done, todo docs

[219-allow-an-option-value-to-be-set-from-an-expression] Checkpoint: to do add action logs and doc

[219-allow-an-option-value-to-be-set-from-an-expression] Checkpoint: almost finished

[219-allow-an-option-value-to-be-set-from-an-expression] Checkpoint: wrote flex option code, to do tests, to finish doc

[677-kea4-not-honouring-the-p-switch] Added ChangeLog for -p switch improvement

[677-kea4-not-honouring-the-p-switch] Improved -p support

[962-implement-the-multi_threading_mgr-h-idea] Added ChangeLog entry for MultiThreadingMgr

[962-implement-the-multi_threading_mgr-h-idea] Fixed doxygen

[962-implement-the-multi_threading_mgr-h-idea] Addressed comments

[962-implement-the-multi_threading_mgr-h-idea] Merged into one class

[962-implement-the-multi_threading_mgr-h-idea] Fixed trivial typo in comment

[962-implement-the-multi_threading_mgr-h-idea] Added the Multi Threading Manager

[#900,!561] Updated ChangeLog

[#900,!561] Addressed review comments

src/lib/dhcp/libdhcp++.cc
    Cleaned up necessary exception decls

src/lib/dhcp/option.h
    Added commentary for SkipThisOptionError

src/lib/dhcp/option_definition.cc
    Cleaned up unnecessary exception decls

src/lib/dhcp/option_string.cc
    Replaced NULL with nul

src/lib/testutils/gtest_utils.h
    Added emissions of exception type name

[#900,!561] kea-dhcp4/6 now quietly drop empty or all-null string options

src/lib/dhcp/option.h
    class SkipThisOptionError - new exception type

src/lib/dhcp/libdhcp++.cc
    LibDHCP::unpackOptions4()
    LibDHCP::unpackOptions6() - explicitly catches and handles
    SkipThisOptionError expceptions

src/lib/dhcp/option_definition.cc
    OptionDefinition::optionFactory() - now rethrows SkipThisOptionError

src/lib/dhcp/option_int.h
    OptionInt::unpack() - altered ambiguous exception text

src/lib/dhcp/option_int_array.h
    OptionIntArray::unpack() - altered ambiguous exception text

src/lib/dhcp/option_string.cc
    OptionString::unpack() - now throws SkipThisOptionError if option, once
    trimmed, is empty

src/lib/dhcp/tests/option_string_unittest.cc
    Updated tests

src/lib/dhcp/tests/pkt4_unittest.cc
    TEST_F(Pkt4Test, testSkipThisOptionError) - new test

src/lib/dhcp/tests/pkt6_unittest.cc
    TEST_F(Pkt6Test, testSkipThisOptionError) - new test

src/lib/dhcpsrv/tests/cfg_option_unittest.cc
    Updated expected exception text

src/lib/testutils/gtest_utils.h
    Added two macros to emit exception info on throws.
    #define EXPECT_NO_THROW_LOG(statement)
    #define ASSERT_NO_THROW_LOG(statement)

[919-bind1st-and-bind2nd-were-deprecated] Added ChangeLog entry for bind1st/bind2nd

[919-bind1st-and-bind2nd-were-deprecated] Updated bind1st/bind2nd with bind or lambda

[868-the-examples-directory-in-main-dir-not-doc-examples-is-useless-and-should-be-removed] Removes topdir examples

[master] Fixed ChangeLog last inserted entry

[937-doc-should-mention-rfc8357-relay-port-as-supported] Added RFC 8357 support in doc

[497-kea-uses-deprecated-header] Fixed boost/{integer,math}/common_factor.h

[497-kea-uses-deprecated-header] Revert "[497-kea-uses-deprecated-header] Reverted the -isystem"

This reverts commit 9c1ab2136422d20d916338d210708074a412d502.