Add a setVertexBuffer method to context as it is not always required to set multiple buffers. So we can save creating a temporary list (as in setMesh)
Merge pull request #139 from Fox32/feature/set-vertex-buffer

Add a setVertexBuffer
Add addQuad to debug draw manager
Fix indentation
Merge pull request #143 from Fox32/feature/debugdrawmanager-addquad

Add addQuad to debug draw manager
Improve draw buffers performance by setting it on draw only if it has changed.
Merge pull request #145 from Fox32/feature/drawbuffers-performance

Improve drawbuffers performance
We already know about the current program that is in use. So we can skip calling getParameter here, doing it for every constant is not a good idea. In general we should not call getParameter as it slow.
Merge pull request #146 from Fox32/feature/avoid-get-parameter

Avoid using getParameter in setConstant