Implement sidechaining in the engine and plugin engines.  Still need to
implement in the UI and create at least one plugin that supports it.
Implement the intial data/UI sidechain stuff...
Partial implementation of a sidechain compressor...
The sidechain compressor compiles!  (but not tested yet)
Various fixes to the new sidechain compressor.
Fix switch/case falling through to the default instead of breaking.
Fix sidechain buffers not getting connected.
Better knob values displayed.
Doh!  Forgot to convert the dB value back to linear...
The sidechain compressor does work now, but some more DSP wizardry
 is still needed to make it sound magical...
Fix a memory error found with Valgrind...
Color-code the wires going to sidechain inputs red in the routing graph.