support more than 8 channels

[marclava]

I need 24 channels (recording, playback, editing) with jackd. Opening and browsing a large muti-channel file is already working, but playing it crashes the software.

[magnush]

As mentioned in other issue thread:
There are places in the code where it's hardcoded assumption of max 8 channels, like local array variables that are allocated. So one would have to find all those places, and replace them with a constant MAXCHANS, then after that you could just increase that constant. One way to find the bad spots may be to run under valgrind and see in what functions it starts doing bad things with memory, another way to find clues be to search for the constant 8 in the code.