Add untested channel splitters/mergers.
Start of rearrangement of DSP items.
Add namespaces to DSP units
Update thelonious.h for new layout of DSP units.
Fix parameters in cubic interpolation.
Add include guards in audio_device_ofx so it can conditionally compile
as a standalone unit.
Fix split/merge typedefs.
Remove compile test files and add an automatic compilation tester to the
the Makefile.
Use find to gather tests in Makefile.
Add constant unit, and use it to create silence unit.
Give split a more useful default number of channels
Add tests for split.
Make merge zero extra channels on output.
Add select units, and tests more tests for multichannel units.
Small test Makefile changes