[Fluxus] compressor update

[Kassen]

Dear list,

For the redacted branch I replaced Fluxa's compressor with a 
adaptation of the one from ChucK (also GPLv2).
That one is by Matt Hoffman and Graham Coleman and works quite well
for our puroses, IMHO. I also think it should be lighter on the CPU
than the original design, though of course not lighter than the
original while commented out :-). It's a simple hard-knee design
without fancy lookahead, but it should serve, I think the attack and
decay functionality is a lot better.

I kept the default settings where they were which means that under
normal conditions you couldn't tell the difference as Fluxa's default
volume is quite modest and you'd need to add a lot of different sounds
together to reach the default treshold. Under normal conditions then
the compressor will protect your highly dynamic composition from
clipping.

I'm sure that suits everyone's needs, but to address the purely
hypothetical case that somebody might at some point like to use Fluxa
to play lo-fi acid gabber in a so-called "night-club" environment I
added a optional "boost" parameter which sets the slope for amplitudes
beneath the threshold. This one defaults to 1 and settings up to 2
should take care of most common needs. (mind your ears, speakers and
neighbours).


Yours,
Kas.