removed one comment and added SIPL_USE_GTK check on compilation of tests
Merge branch 'unstable' of github.com:smistad/Tube-Segmentation-Framework into unstable

Conflicts:
	tube-segmentation.cpp
Updated OCL utilties to mac_compilation_2 branch
fixed bug in tube validation: one volume was not initialized
Merge branch 'unstable' of github.com:smistad/Tube-Segmentation-Framework into unstable