TODO

Performance
- Implement the remainder of the incremental parsing algorithm: re-use parse tree after the edit
- Optimize grammar compilation
Error handling
- Preserve tokens within error nodes
- Try to minimize size of error node by looking ahead a few tokens
Grammar Features
- Indentation tokens
- Regexp assertions
  - '^'
  - '$'
  - '\b'
- Composing languages
  - Rule for referencing named grammar
  - Grammar registry object in runtime
  - Parsing returns control to parent language
Grammars
- C
- Go
Query API
- closest(node name)
- find(node name)