Change local definition of PI to M_PI

Follow convention from other parts of Antelope and use the M_PI macro
instead of calculating our own locally.
re-init the outse channel pointer
refactor proc thread
Add noise to synthetics, static tag private funcs

Simulate digitizer noise in the synthetic signals by adding random noise

Declare various private functions as being static so that they don't
pollute the global namespace
change duration to be a referenced param
Move single use macro definition

Placed right before function declaration
Merge branch 'outfilter'