Abstract over lists and vectors for BufferObjects.

Add a helper for creating a buffer of Word32 indices. This is
particularly handy because it means the client often doesn't need to
import Data.Word anymore.
Helper for drawing indexed triangles.
Added 2D and 3D cameras based on linear.

These modules are not exported by Graphics.GLUtil, but are provided to
obviate the need for constant reinvention of this particular wheel.