WIP: Ability to repack exported data

/u/impiaa has been working on this. Will merge when he says it's finished.

See also #3 (closed)

TODO

• string offsets: don't use strings.json
• change default output settings for project files so they make sense (no strings.json, output 'raw' bytecode, dump unknown chunks, ...)
• make the code more robust, and add error handling (currently none in the JSON parser)
• stuff with chunks:
  • skip empty chunks
  • include unknown chunks verbatim
  • try to preserve chunk order
• CodeInfo uses hacks to go around the limitation of the pointer stuff that makes no sense when parsing .asm files
  • either rewrite it (would fit in #25), or do... something?
• find out unknown stuff getting in the way of proper repacking
  • object path stuff
  • variable attributes
• find out how linking works
• would be nice: recompile .gml.lsp code