Change: parse result produced for quoted string is an object (AST node) instead of the string itself.
Refactor: test code to make it reusable
Add: comment parsing
Add: log parsing
Refactor: rename AST node types. Add: 'log to error' parsing.
Add: number parsing. Fix: use description in error message when assertion fails.
Add: operator parsing. Improve: syntax error reporting in test.
Add: variable parsing
Add: tests for parsing empty strings
Reorganize spec.md so related sections are close to each other. Other changes based on 'dream.jsh'. Removed some unnecessary detail from the spec.
Refactor: introduce "literal" and "expression" in the grammar
Add: whitespace parsing
Change: value of the variable AST node no longer stores the '$' prefix
Add: comparison parser