Remove deprecated GL calls, comply with 4.2/3.3 core profile. Use VAO, update glsl shaders, remove immediate draws, etc.
In example code, GLUT has been replaced with GLFW so that glViewer/ptexViewer can run on OSX (10.7 or later).

OSX note: still have some problem with clang, may need to explicitly specify gcc on cmake cmdline
 -DCMAKE_CXX_COMPILE=/usr/bin/g++

fixes #98
Fixed a buffer overrun error in OsdCLGLVertexBuffer::UpdateData.
Merge pull request #99 from njlitke/master

Fixed a buffer overrun error in OsdCLGLVertexBuffer::UpdateData.
bail out of Rebuild call if the VBO / VAO have not been allocated yet.

fixes #100
Merge branch 'master' of github.com:PixarAnimationStudios/OpenSubdiv
bail out of Rebuild call if the VBO / VAO have not been allocated yet.

fixes #100
change access permissions on files
exclude .inc.rule files generated by MSVC
- add cmake logic to parse package versions and include the correct headers
- add #ifdefs to work around the different versions of glfw
- add cmake logic to parse other packages versions and set minimum requirements
- fix X11 dependencies for static builds of glfw

- general Find.cmake cleanup

fixes #101
add glfw3 to windows section of glfw module

fixes #101
migrate osd_regression from GLUT to GLFW (this regression still needs work)

fixes #98
Merge branch 'master' of github.com:PixarAnimationStudios/OpenSubdiv
docs: GLUT -> GLFW
fix the OSD version printout in top CMakeList (now based off the #define in opensubdiv/version.h)
Update README.md
Merge pull request #102 from aras-p/master

update readme about GLFW
fix linking with GLFW link on OSX
Merge pull request #104 from aras-p/master

Fix OSX build of examples that use GLFW
gcd: files for GCD dispatcher (right now just copy of OMP one), add items to glViewer
gcd: naive implementation using dispatch_apply for all loops. Not faster, dispatch overhead too high