[preview] Adapt to upstream changes
This adapts the config dialog to upstream changes (uses Settings instead of Options).
Solved:
What is not working correctly: The spin button's value throws a warning in settings.py
when the value is > 128
Warning: value "301" of type 'gint' is invalid or out of range for property 'setting-value' of type 'gint'
Edited by Daniel Brötzmann