Changed _SymbolTable to _SymbolTableList for multiple scopes
Updated symbol table display to display multiple tables (scopes)
Added ast.js and created global var _AST
No longer modifying source code in lex

No longer modifying source code when the user forgets the EOF token or
places text after the EOF token
Fixed the off by 1 issue when displaying the symbol table(s)
Introduced scope to parser.js and improved symbol table construction