Added unit tests for Callback accessors and updated POD for completeness
Fixed warning on double declaration of $pid
updated documentation
v1.07
Updated changes for version 1.07
Added information about git
Merge remote-tracking branch 'upstream/master'

Conflicts:
	lib/IPC/Open3/Callback.pm
	t/Callback.t
merge with original repository of IPC::Open3::Callback
added the automatic testing of POD