Refactored the CLI stuff

This replaces the old opt parser with something that's a bit nicer. CLI tools now simply need to inherit from DokuCLI and can register the options, arguments and commands they want to accept. The base class then takes care of parsing the command line options, builds a usage help and also provides some convenience functions for colored text output.

All CLI tools have been refactored to use the new class and also cleaned up a lot. The old stuff has been deprecated.