[REQ] Purge list

If you a die hard MPC user you had probably already mess with the PURGE function

So simple request but as this function can be long and frustrating, showing which samples will be purged and adding a completion percentage could be useful.

Not the request of the year I must admit

But it's a good one... happened to me couple of times that i've forgotten to add new samples to a program and lost them when purging.

+1 from here. Especially when deleting a program including sample purge it'd be better to only remove the program's samples and not ALL unassigned samples.

Moreover - I'd prefer to have an ability to purge all samples not used in any track. Sometimes there are so many samples that are assigned to program but aren't (will not be) used in any track. Especially when I use my standard, pre-composed program from another project.