Only detect articulation change via direct keyswitch when output events have a single event

[jtackaberry]

Currently if any one of the MIDI events in the set of output events for an articulation is detected, Reaticulate will reflect the articulation change in the GUI.

This is a feature meant to detect direct keyswitch changes that bypass Reaticulate. But when there are multiple output events, it exhibits unexpected behavior.

Only implement this behavior when there is a single output event for a given articulation.