Samples and test builds can be disabled with cmake variables. kglt::App constructor can now receive window size and other args.
Merge remote-tracking branch 'upstream/master'

Conflicts:
	kglt/application.cpp
	kglt/application.h
Merge branch 'master' of github.com:Kazade/KGLT
Merge remote-tracking branch 'upstream/master'

Conflicts:
	CMakeLists.txt
Merge remote-tracking branch 'upstream/master'
Implemented Camera::look_at(..) method. It is very simple, thanks to Kazmath, but there seems to be a bug in light_sample.
Merge commit '3ac5b3cf43b33117013d2e2dcc04461e8f021393'