TODO

- Remove globals in sysposix.c
- Fix see for deferred words
- More C types in FFI
- Print line numbers in errors for the terminal.
- blocks
- negative strings?
- fast dictionary search using endian-specific code, i.e
   if (((*(CELL*)cstr1) << 3) == ((*(CELL*)cstr2) << 3)) ...
- factorize INTERPRET with something like FOREACHPARSED
- document
- split ?dodefine -> ?xt+xtbody
- more file tests
- forlist/repeat?
- implement user and remove fake definition from host-fina.fs
- remove debug stuff (shifts, type2, rdepth, rpick...)
- split docreate -> dovar+dodoes
- cross-compiling support
- implement as primitives:
   >= u> u>= <> 0<> dofor do?do lshift rshift arshift 
   fm/mod mod / 0 -1 1 perform