simpler lex/parser

[crgimenes]

To make it simpler to add new features and receive more contributions my suggestion is to rewrite the parser / lex as in this example I wrote some time ago.

https://github.com/rumlang/exp/tree/master/lex

The idea is a lexer with some interesting features such as read only to forward, this enabling you to receive the code via stream, ease to include new structures and also be easy to debug, avoid generating panic, instead give a more elegant message instead of the traceback in Go.