Fix crashes when using rather low-end cards like Intel ones

Solved by checking on run-time whether texture buffer objects
are supported.

When building with GLEW library doing compile-time check is
not enough, because actual information about existing features
is only known on runtime.

This only makes ti so CPU backend works, GLSL backends still
requires some work if we want them to make working. Not sure
it worth doing this now.
Merge pull request #330 from Nazg-Gul/dev

Fix crashes when using rather low-end cards like Intel ones