Use CMAKE_CXX_FLAGS so that linker gets the right flags.
Enable glewExperimental for MacOS X due to misreported extensions.
Open glfw window using forward compatible OpenGL 3 context.
Fix building with non-X11 OpenGL on MacOS X.
Update README.rst to reflect MacOS X support.
Force MacOS X to use OpenGL 3.2; thats the maximum it currently supports.
012_checker_sphere updated to be compatible with MacOS X.

Using index buffer objects as MacOS X does not support index arrays
being passed directly to glDrawElements (OpenGL implementation bug?).
Removed some redundant code from 012_checker_sphere.
013_spiral_sphere updated to be compatible with MacOS X.
016_cartoon_torus updated to be compatible with MacOS X.

gl.LineWidth(4.0f) does not work as in the core 3.2 profile.
016_noise_torus updated to be compatible with MacOS X.
016_metallic_torus updated to be compatible with MacOS X.
017_clipped_torus updated to be compatible with MacOS X.
017_phong_torus updated to be compatible with MacOS X.
018_newton_landscape updated to be compatible with MacOS X.
Add missing comment in 018_newton_landscape.
020_checkered_objects updated to be compatible with MacOS X.
020_shaded_objects updated to be compatible with MacOS X.