0.2.1

• separate initialization for constants and levels
• allow negative constants in the grammar
• allow expressions in constant lists
• show code generator exceptions for debugging purposes
• add the "subs" tool to generate the JSON for subscript ranges
• make the RHS optional to support the syntax for loading data files
• expand preprocessor to extract manually handled constructs to a removals.txt file
• format code with prettier (no more semicolons!)