Add dry contact option to remap red/ctrl to stop

[PaulWieland]

Some commercial GDOs do not have a single button control interface. This means that there is no way to partially open the door since we do not have a dedicated stop output in the current firmware.

Ideas:

• implement a user setting that re-maps the red/ctrl output to stop
• change red/ctrl to stop on the dry contact firmware and require Single Button Control dry contact installs to connect both SO/SD to the SBC terminal (cleaner implementation but makes most DC installs more complicated)