Signed-off-by: Cyrille Bollu <cyrpub@bollu.be>

Signed-off-by: Christoph Wurst <christoph@winzerhof-wurst.at>

* Restructure code into separate, testable units
* Add unit tests

Signed-off-by: Christoph Wurst <christoph@winzerhof-wurst.at>

- Modifications from commit 01fcff9a294f57652c669254f0f8aa57607009e8 by
  Christoph Wurst have been imported and adapted for the current version.
- Some changes have been written already in order for the changes to work.
- Name of Christoph Wurst has been kept in @author metadata.

Signed-off-by: Joas Schilling <coding@schilljs.com>