remove duplicate truncated ztree API reference
Merge pull request #276 from claws/upstream

remove duplicate truncated ztree API reference
Added support for using zctx_shadow on a context which didn't create sockets yet
Merge pull request #279 from MCE-KobyBo/master

Added support for using zctx_shadow on a context which didn't create any sockets yet
Merge pull request #280 from hintjens/master

Classes that return allocated values now provide a free method
zmonitor addition
Merge pull request #281 from claws/zmonitor_addition

zmonitor addition
Code cleanups