Merge pull request #1 from ratefuchs/master

Deleted .iml and put it into gitignore, commented out import of non-exis...
Fix several bugs and code style issues.

Thanks to Simon Bischof for remarks that resulted in this commit,
improving the lexer.
Improve lexing of numeric literals and add tests.
Improve float literal syntax.
Allow scientific notation and dissallow '.' as a valid float literal.