Bump MAX_BPI to 128, to make jazz players happy

[brunorc]

I was in the proces of creating some predefined Ninjam sessions and testing the outcome. I was surprised to see that even though I've set DefaultBPI to 128, the loop was still 16 bars long. I wanted to have two sessions tweaked for jazz standards, which are in most cases 32 bars long, and while I can still do /bpi 128 and it will work, I thought it would be nicer to do it from the config file.

[mk030166]

Hi. I join this request too. Is it possible to make sure to bring the MAX BPI to 128 or even more and possibly lower the MIN BPM to 20? Thanks!