Improve fused increment design

[charleskawczynski]

We could probably improve the fused increment design in two ways:

• Reduce the amount of information in the type space (Add support for fused incrementing #249 (comment))
• Remove the use of generated functions.

Since the bit information is known at compile-time, we could use a recursion to create the broadcast expression (so that it remains statically inlined).

[charleskawczynski]

#250 fixed the inference issue, and implemented the kernel fusion.