- implement pre- and post-exec commands
   o For the general backup process
   o source specific
   o what to do with return values?

- Documentation
   - write/generate a manpage
   - rsync_options \n seperated


DONE
- implement verbosity
   o per source (-v to rsync)
   o general, very verbose (set -x)
- implement parallel execution
- implement general log
- implement source specific log (canceled)
- the name prefix is currently somehow inconsistent
- Documentation
   - rsync_options, example paswd
   - write a simple manual
   - Hints section
   - add note to --exclude=/proc/ vs. --exclude=/proc/*