Add Scope class (#34)
Create TigerNode placeholder class
Start TigerFunction class (#34)
Changes to grammar to simplify tree walking; parser code changes (#34)
All function declarations + param passing is now in funct_declaration
Whoops, defineFunction should be in parser::members (#34)
Rename Function -> TigerFunction (#34)
Update tree grammar (#34)
Cleanup grammar formatting
Implement walking parse tree, evaluation next (closes #31)