Added compatibility with GLFW3

[paperManu]

This patch allows the use of GLV with GLFW, by setting the flag GLV_GLFW.

[LancePutnam]

Do you know if this patch also works for OSX and Windows? Otherwise, it's fine as Linux-only for now.

[paperManu]

I didn't have the opportunity to test it on anything but Linux, though I guess it should work on OSX too.

[DrewRWx]

I did a brief test on OS X 10.9 by modifying the OS X elif clause like the Linux one. There's an issue with GLV_PLATFORM_INIT_CONTEXT not being defined, but commenting out that function call allows the example to compile and run, albeit without the screen tearing prevention that the #define provided.

Unless I'm missing something, it looks like this commit allows including GLFW headers, which also wrap including OpenGL heads, but doesn't make use of them and instead still uses GLUT.

[paperManu]

Should this be ported to Windows before merging?

[DrewRWx]

Yeah, Windows support is a priority for one of our architects.