When looking for a number in an index register, if we can generate it with a inc/dec, do so (saving one byte vs reloading it). Quite a lot of cost savings size-wise.
When looking for a number in an index register, if we can generate it with a
inc/dec, do so (saving one byte vs reloading it). Quite a lot of cost savings
size-wise.

The Standard Benchmark is now down to 7m17s, so it makes things a tiny bit
faster.

davidgiven/cowgol,davidgiven/cowgol