tempo.do() and onset.do() return a single value only instead of an array

[rewbs]

I believe that in the underlying Aubio implementation, tempo.do() and onset.do() return vectors containing all beat and onset event locations within the last processed buffer.

However, the methods exposed in JS return only a single value:

• https://github.com/qiuxiang/aubiojs/blob/main/src/tempo.cc#L24
• https://github.com/qiuxiang/aubiojs/blob/main/src/onset.cc#L31

This means that with tempo, we can't get the estimated location of each beat, and with onset we can only get the last onset event.

[rewbs]

Actually, ignore that – I see now that the returned vector is actually of size 1 (as documented in https://aubio.org/doc/latest/onset_8h.html#a3329b2f251f75556a08bc56ae57cb5fa ).