macros with the same name as a build-in mnemonic?

------------
.COD file support (and remove .sym support?)

- named macro arguments?

not documented yet:
  CBLOCK (MPASM-style)
  _PICASM version number
  __<pic_type> not documented..

---------
??
- free all memory on exit, do not rely on automatic free
- always use mem_free(), not free() (a couple of cases in token.c)
- output to console (stderr) with special function
- otherwise make code re-entrant

