Bugs fixed:
- %= and the new assignment operators were not emitting error on invalid types.
- List globals referenced in another global were duplicated entirely.
- Properly recognize -option in the command line.
Rest:
- Complete overhaul of the internal data structure.
- Got rid of the symbol table plus mini-trees, and made everything one big tree plus an auxiliary symbol table.
- No more special case hacks like using tuples instead of lists...
- Got rid of the EXPR hack.
- Dict-based, rather than list-based. Allows adding arbitrary data to any node or symbol entry.
- Added a few coverage tests for the new code.
- Return values can now be chained; the functions parameter requirement is gone. Still not fully convinced, though. My guess is that a parser object should be passed between functions instead. Will do for now.