Add a changelog.

Bump version to 0.7.2.1.

Add Enum instances to AccessNature and AccessFrequency.

Bump version to 0.7.1.1 (bug fix).

Bump version back to 0.7.1.0 for Hackage release.

Fix package description mistake.

Comment about API stability.

The API has been broken a few times and I don't consider things to be stable
yet. I think I should mention that in the READMEs and descriptions.

Modify library description wording.

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.

Advertise generalization over MonadIO.