Further expand array sizes (#52)

Replaces the existing ad hoc array size selections with the following,
which cover all current known use cases:

- 0-256
- 272-1024 (multiples of 16)
- 1040-4096 (multiples of 32)

This also effectively reverts #50, since it was adding considerably to
compile times (now noted as a comment in that PR).

Author: tarcieri