Bugfixes

- Velbus VMBGP1-20 VMBGP2-20 VMBGP4-20 Thermostats were not available. This is now resolved
- Modbus: connection stability improvement
- Web interface zone editor: in some cases buttons could not be removed from a zone. This now resolved.
Unrelated to the Home center version
- VMB8IN-20 needs to have firmware version 2551 to work properly with Home center
