Port mbrock's changes done with amp

Almost all landed as of https://github.com/pizlonator/fil-c/commit/b2543021cb14c73dd472a81c457419ced29ec115

These did not land:

• The misaligned pointer constant change. That was unsound. It introduces a GC bug.
• The sarcasm semicolon change. I will land it eventually, but right now it badly conflicts with other changes I made in sarcasm.