[#35,!517] Added hostname-char-set to hostname-char-replacement network/subnet scopes

[#35,!517] Added hostname-char-set to hostname-char-replacement network/subnet scopes

src/lib/dhcpsrv/d2_client_cfg.*
    Added hostname-char-set and hostname-char-replacement to DdnsParms
    DdnsParams::getHostnameSanitizer()  - new function to return a sanitizer

src/lib/dhcpsrv/d2_client_mgr.h
    D2ClientMgr::adjustDomainName() - now gets sanitizer from ddns_params

src/lib/dhcpsrv/network.*
src/lib/dhcpsrv/parsers/base_network_parser.cc
src/lib/dhcpsrv/parsers/simple_parser4.cc
src/lib/dhcpsrv/parsers/simple_parser6.cc
    Added hostname-char-set and hostname-char-replacement to networks and subnets