Tempo stuff (time-shifting et al)

me again, trying and failing to make extremely loud music because that's how the natural order of the universe is structured. here's two suggestions from an idiot who has no idea what she's doin':

the (theoretically) easy one: non-integer bpms (two or three decimal places).

the slightly harder one: time-stretching for AFP.

i'm aiming to recreate the sounds of experimental hardcore, especially those from hcn, hangars liquides and bloody fist records. the latter's artists produced a lot of lo-fi jungle and breakbeat hardcore in addition to the usual angry hardcore and speedcore.

rn i'm busy trying to get some break loops into my tracks whilst using vsts over wine to make some dirty kicks. however, being the pedantic mess i am, i tend to get obsessive about timings and using AFP by itself doesn't do the trick. however, searching for a free vst that can perform time-stretching (maybe with optional vibrato for the oldschool nuts like me) seems to be a fool's journey!

inb4 learn c++/qt5/synthedit/whatever and code it yourself: doing so is particularly depressing and long for me and for some reason it feels like it's exclusive to me. getting results seldom seems to work, whether it's my environment, the libraries or my code itself. by the time i'm done, i'm bored and i'll have moved on.

The issue proposes non-integer BPM support and time-stretching for AFP, but names no files, tests, or entry points. Start by locating the tempo/BPM handling and AFP audio-processing code, then determine how each request should behave and how it can be tested. Done means both requested capabilities have defined, working behavior.

Written by the indexing model from the issue text.