Allow grid to start at non-zero value

[CNelias]

The current version of quantize() excpects a grid to start at 0 and end at 1.

Some players have a systematics deviation, and removing them makes the music sound strange. It would be good to be able to use grids like [0.09,0.33,0.7,1] for example.

[Datseris]

Although this is a straightforward improvement, a workaround currently is to use the function estimate_delay and estimate_delay_recursive, and shift the notes, then quantize them and then shift them back.

[CNelias]

The workaround is quite trivial indeed, but I'd like to have this feature inside of quantize. I'll see if can implement it today if it's not too complicated.

[Datseris]

@johncwok , what does 1 mean in [0.09,0.33,0.7,1]? Does it mean the next quarter note? then what does 0.09 mean?

I see some difficulties of how your suggestion of not starting at 0 and not ending at 1 can work with quantize.