Improve the README file

Based on the template at http://write-the-docs.readthedocs.org/en/latest/writing/beginners-guide-to-docs/
Fix the syntax for empty regular expressions for Alex3.
BNFC generated '$' for eps but the correct thing to generate is '()'.
Add sphinx-quickstart generated doc
Add lbnf-report converted to rst
Add gitignore
Add the lbnf reference to the doc index
Merge pull request #68 from gdetrez/readme

Improve the README file
Merge pull request #69 from josefs/master

Fix the syntax for empty regular expressions for Alex3.
Merge pull request #72 from gdetrez/doc

Convert the lbnf report to rst