General clean-up, native CLFind, logger and configParser rewritten, calcBackground improved

This is a large commit. Some of the main changes include:
- The configuration file now uses ConfigParser and is read accordingly.
- facyPrint has been substituted by a class. The usage is similar but
should be more versatile.
- getRegions.py has been cleaned and simplified.
- calcBackground (called in interactive mode) now use a two-steps
procedure to determine the background.
- CLFind is now completely Python native and the performance is similar
to IDL.