Enhancment: Given #23, have menu entry to reset overrides to 100%

[thawkins]

Allow overrides to be reset to 100% with a menu entry.

[bdurbrow]

I'll also add this. It will only be present when there is an override menu option available; and will only affect overrides that are menu-driven, not potentiometer driven.

[thawkins]

Noted, that sounds reasonable