Add some newBufferXXX convenience functions.

Now you can quickly create buffers from lists, storable vectors and
bytestrings.
Use GL_ARB_buffer_storage if it is available.

There was a TODO-item on this I spotted. OpenGLRaw didn't have that extension
(which was used before) but we are with flextGL now.

The extension text suggests creating buffers with this extension may increase
performance.