OpenVPN Release 2.7_beta3

OpenVPN Release 2.7_beta3

version.m4, ChangeLog, Changes.rst

Changes.rst has not received an "2.7_beta3" section - it has the
"highlevel" overview of what is new in 2.7, but for alpha/beta releases
it's better to look at git log to see what has been added/fixed.

Notable changes beta2 -> beta3 are:
   - even more of signed/unsigned related warnings have been fixed
   - document that PUSH_UPDATE is (as of now) not compatible with DCO,
     and add adequate checks
   - improvements on PUSH_UPDATE handling on the server side
   - bugfixes reconnect and PUSH_UPDATE handling on the client side
     (notably handling of ifconfig/ifconfig-ipv6/redirect-gateway ipv6
     if the server is not always pushing the same address families)
   - improve "recursive routing checks", prepare the way for a
     policy-based setup where "packets to VPN server" could end up
     in the tunnel without interfering with OpenVPN operations
   - improve unit testing, add more unit tests, fix unit test bugs
   - add support for "eoch" data format to DCO on Windows
     (needs dco-win driver 2.8.0+)
   - clean up and remove outdated stuff from COPYING

Signed-off-by: Gert Doering <gert@greenie.muc.de>