cleaned up saturator code
added accumulator loopback input to multiplier (used for polynomials)
added a metering memory (24 bit x 256 words). It's called 'MMEM' for the in-system memory editor, and from the DSP's point of view it's mapped to io output addresses 1024 to 1279
Added some NOPs after inputs to make sure data from In(0) is available to the first biquad