Enable 2 passthrough inputs.
Unify control names for passthrough enabling across EnginePassthrough and EngineDeck.
2013-05-30: Jog control improvements

- Ignore jog wheel movements unless the jog wheel surface is touched.
  Exception from this rule: Nudging when playing in scratch mode is
  still possible without touching the sensor plate!
- Different jog sensitivity parameters for cueing and nudging (tempo)
- Increased jog sensitivity for both cueing and nudging