Fixed #154 and other constant-related bugs. Also: removed the "feature" of regex literals being automatically assigned to a constant to avoid multiple recompilations of the same regex (users must be able to choose that to)

Fixed type lookup: types were looked up from "self", but they should be looked up from the matching def.

Bootstrap: codegen fun literals and fun pointers (but without trampolines yet). Added —release flag. And other small fixes.