Previously, all calculations regarding stack depth and label depth
were broken. *All* of them. Off-by-ones, the logic was wrong, etc.
Variables are still screwed up, but I'm *almost* there, where
"there" is being able to generate functioning programs, hopefully?
Still pretty horribly broken. I was generating dispacements
backwards, failing to emit stuff like the beginning of
loops, the logic for `if` jumps was backwards, etc.
I was also completely forgetting to increment file_here
for appends. I don't remember what all I did; check the diff.