Add check for encoder support.

[chattob]

@GuitarML @xconverge don't you guys have issues with the Funbox?

I have a similar pedal variation (no encoder, no display). When I press the alternate footswith I often get the active effect changing to the next one on the list. This happens because of this code section:
// If alt footswitch held AND encoder turned, iterate to next/previous effect, also throttle the changes const int encoderIncrement = hardware.encoders[0].Increment();

Because the encodersvector is empty I get random non-zero values for Increment().
This PR defines explicitely if the pedal variation has an encoder or not.

[xconverge]

I only recently made a funbox and added the support to this repo. Whatever I was testing didn't involve the alternate foot switch so I didn't notice

This makes sense though!