- Renamed literal Types to reflect their literal nature
- This allows for consistent naming across future non-literal Types
- Complicated lexer Rules have been split into composable sub-rules,
and moved into the Rule struct.
- This improves modularity, and allows sharing of sub-rules across rules.
- Documented each lexer rule with (at least) a one-line blurb
describing its function
- Lexer now ignores leading whitespace
- Rule now has shorter, clearer function names
- Tests for comment lexing are now consolidated into a module
- Tests using the assert_has_type_and_len wrapper can now specify
an expected length
