replaced re with regex

There are a lot of errors because of "look-behind requires fixed-width pattern".

Using regex (https://pypi.python.org/pypi/regex) instead of re allows us to compile every available pattern.

Loaded 3596 rules (0 errors, 43 disabled)
Merge pull request #6 from berendt/replace_re_with_regex

replaced re with regex
Using regex module enabled more rules, some aren't useful

From: https://gist.github.com/berendt/1e88ecb974e16fbe2238
Thanks to: Christian Berendt <berendt@b1-systems.de>
Use logging instead of print

Written by Berendt, rebased & modified slightly by Marti.
Use default 'python' in shebang, not 'python3'
Refactor into functions, allow importing as a module
Handle errors when file open fails