Major changes, fix memory leaks, add functionality, pythonise

Create ADC & DDS Class Libraries.
Incorporate RPi VoltMeter and modify to use the ADC Module.
Create RPi SignalGen (rpi_signalgen.py) using DDS Module.
Modify RPi Wobbulator to use the ADC & DDS Modules.
Extensively modify RPi Wobbulator, conforming to Python conventions.

Signed-off-by: Gray Remlin <gryrmln@gmail.com>