Added Cocoa to TKService toolkit - Added Cocoa lib dependency
Added .mm ObjC source files on OSX
Replaced OSX X11 OpenGL with native Cocoa OpenGL implementation
Use OpenGL/*h headers on OSX
Unnecessary to include GL/glu.h since OpenGl_GlCore11.hxx is already included
Include <OpenGl_GlCore11.hxx> wherever OpenGl headers are required
Added Cocoa OpenGl as a cmake option disabled by default
[OCCT] 0023682: Implement Draw_Window with Cocoa framework

Implemented most Draw_Window functions with Cocoa. Still should be implemented: drawing rectangle when zooming, window screenshot function in QAxwd
Added workaround for drawing rectangle when zooming
Added small fixes

  Cherry-picked from
    http://git.dev.opencascade.org/gitweb/?p=occt.git;a=commit;h=67d97f0
  * Header files are located under inc/ in OCE.
  * Conflicts in EXTERNLIB files have to be resolved.
OSX uses default Tcl/Tk if ever MACOSX_USE_GLX is not defined
Ugly hack to remove X compilation issues