Parser evaluates expressions via shunting yard algorithm.
Parser now works with parentheses on expressions.
Handle syntax errors a bit more gracefully.
Clear parser's token list upon syntax error
Handle unary minus sign.
Renamed old parser to LiveParser which uses Shunting Yard algorithm.
Replaced with new Parser class which builds an AST via operator-precedence parsing before evaluating.
Minor cleanups.
Merge branch 'master' of https://github.com/NickManley/Slang.git