* Fix reset on timeout: Reset needs to be called before
processing any messages.
* use DLL to compute BPM (remove 1st order LPF)
* set BPM before calculating ppqn
* Fix speed at 1.0, change BPM only. MIDI clock must
vari-speed (which changes pitch). MIDI clock is acts as
"Conductor" that specifies when a beat happens at a given
wall-clock time. timecode moves at speed 1.0 only the BPM
changes.