Add rotation and color support for Quad and Sprite types

[hecrj]

As of now, there is no way to set a rotation/color per quad/sprite. This is a really basic feature.

We could add support for it easily here and here. However, some games do not really need to use this feature and sending additional data to the GPU has a cost.

Before implementing this, I think we should write some basic benchmarks so we can discuss how to proceed (see #13). Maybe the overhead is negligible (I doubt it)? Maybe we can implement a different pipeline with a different shader and smartly select it at runtime? Maybe instanced drawing is not a good idea once we add more data? Maybe we can add it as a feature?