adds pathlib support
add pathlib to build.py
Remove the pkgconfig removals!

This breaks a lot of code when you use pkg-congfig,
it was actually trashing the whole of conda...
Add GTK for OpenCV linux builds

Pretty big dependancy but a requirement for linux
if you want to render anything (such as for the tracker).
Tested on Linux 64 but Linux 32 has been uploaded but
untested due to a lack of current 32-bit windoweded environment
for build (I'm cross-compiling).
Merge branch 'master' into dlib