Enable C++11 support.  This is not used by ohNet but is required if a static ohNet library is to be consumed by a project which does require C++11 features.
Fix various valgrind warnings about accesses to uninitialised and freed memory
Add nocpp11=yes build option for Posix clients targetting old systems without C++11 support.
Merge branch 'master' of ssh://core.linn.co.uk/home/git/ohnet
Enabling C++11 support seems to degrade the version of C supported
Our macs tend to have pretty old versions of gcc installed.  Disable C++11 support for all automated builds/tests for now.
Merge branch 'master' of ssh://core.linn.co.uk/home/git/ohnet
We only need to explicitly request C99 support if C++11 is enabled.