Show interpreted BPM from MIDI clock ticks

[krevis]

If a MIDI Monitor window receives MIDI clock events, use the timestamps to interpolate the expected BPM from the duration between the events.

Would be nice to display this, and possibly other transport information (running, stopped, etc.)

(The hard part may be in smoothing/interpolating to deal with the jitter between clock ticks. What would be useful to show -- raw values, some value of smoothing, or more?)