[Graphics] Add OpenGL error detection to the new calli-based bindings

[opentk]

[Graphics] Add OpenGL error detection to the new calli-based bindings

[thefiddler]

Postponing to 1.2

[Frassle]

Started making some progress on this in my fork, very hardcoded at the moment but wraps around OpenGL calls.

[thefiddler]

Awesome, thanks for looking into this!

The previous implementation used the following hard-coded rules:

1. Every call is surrounded by using (new ErrorHelper(GraphicsContext.CurrentContext)) { /* actual call */ }
2. GL.GetError() is not surrounded, as that would cause infinite recursion.
3. GL.Begin() sets GraphicsContext.CurrentContext.ErrorChecking = false; before the OpenGL call.
4. GL.End() sets GraphicsContext.CurrentContext.ErrorChecking = true; after the OpenGL call.

The reason for 3 and 4 is that it is an error to call GL.GetError() inside a begin-end region, so ErrorChecking = false temporarily turns off error checking.

The original generated code is available here (warning, large file).

[Frassle]

Would like someone to just double check the code, it probably needs a cleanup but it's functional. https://github.com/Frassle/opentk/tree/develop

Also should I rewrite history before pull request?

[thefiddler]

Please rebase against opentk/develop before issuing the PR. I'll double check the code to make sure it works as expected on .Net and Mono.

[Frassle]

OK, I'm going to make some final tidy ups and get to to work for other namespaces not just OpenTK.OpenGL then I'll submit the pull request.

[thefiddler]

This is now merged.