Cosmetic: make some style changes to make it look more like the rest of the compiler

@maxsnew, I really want to make this more transparent and clear, sorry
for the total lack of clarity. Right now this is mostly “I prefer it
this way” and it’d be good to write down a set of rules and then
actually assess of that is a good way to write code.
Make the char parser more restrictive to try to get better errors.

Before it permitted sequences of unescaped chars.