Clean up pseudocode to match planned syntax for the type- and memory-safe
level-2 Mu language.
http://akkartik.name/post/mu-2019-2 is already out of date.
Move stack operations to a layer of their own.
It was some short-term pain to take out the syntax sugar from it, but we
need access to this layer from braces, which can't depend on sugar since
it's part of sugar. Just simpler to keep one clear line and not have to
build sometimes with some sugar but not others.
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.
Kartik Agaram