2.4 - More-Optimal Incrementor

[Draco18s]

While it is possible to do it in fewer components this uses fewer NAND gates (basically we swapped 16 full adders for 16 half adders, because we're adding only a single bit to a 16 bit number, rather than two 16 bit numbers: we just need to ripple the carry across as needed, since the other 15 bits of the second input value are always going to be 0).

This saves something like 432 NAND gates across the whole computer.

[Draco18s]

Ref simpler computer.

A few other puzzles also use fewer NAND gates due to the inclusion of the simplified increment, but their solutions ultimately don't change (just that the total NAND gate count goes down).