Remove explicit vertices, buffering.

Having explicit Float32Array vertices makes some performance
enhancements more annoying to deal with. The explicit buffer step is
also unnecessary and enforces a specific way of handling buffering that
isn't necessarily optimal for every occassion.
Add convenient memory wrappers.

The memory wrappers wrap arrayish objects (arrays, typed arrays, etc)
and provide convenient set/get interfaces. This allows easy
implementation of shared memory blocks, so that batching is more
efficient.