Rename a few scripts to be more consistent.
I'm also starting to feel the urge to bud off `subx run` into its own program,
say tools/emulate_x86. It doesn't really rely on the SubX notation at all.
And then I could rename `subx translate` to `translate_subx_bootstrap`.
Only problem: the commands in the Readme get verbose. But the Readme is
gonna need surgery soon anyway to put translate_mu front and center.
This undoes 5672 in favor of a new plan:
Layers 000 - 099 are for running without syntax sugar. We use them for
building syntax-sugar passes.
Layers 100 and up are for running with all syntax sugar.
The layers are arranged in approximate order so more phases rely on earlier
layers than later ones.
I plan to not use intermediate syntax sugar (just sigils without calls,
or sigils and calls without braces) anywhere except in the specific passes
implementing them.