Instead of an array of strings, just have a character array; that
reduces the size of canned macros by up to 30%, and we only did
sequential access anyway.
Add a builtin equivalent to the %include directive called %use.
%use includes a standard macro file compiled into the binary; these
come from the macros/ directory in the source code.
The idea here is to be able to provide optional macro packages with
the distribution, without adding complex host filesystem dependencies.
The disassembler code gets cleaner if we do *not* separate out the
conditional instructions; instead, rely on the fact that the
conditionals are always at the end and use FIRST_COND_OPCODE as a
barrier.
