Crossover testing

Set up some internal loops to test the software crossover setups. Currently crossing at 80 and 48000, pretty steep slopes. Running the test noise for a while also revealed that I'm getting some rare xruns which I need to deal with. Going to look into adjusting the PCI bus priorities (isn't cpu as its currently only consuming 20% at 2 steps under max).

Input Signal
Output to Sub (Pre-DA conversion)
Output to Woofer (Pre-DA conversion)
Output to Tweeter (Pre-DA conversion)

Octave script used to generate the crossover fir filters - Note that Gentoo users need to emerge octave-forge in addition to octave in order for the script to work.