iotool initial prototype

This initial prototype showcases iotool and the AGP01 board:

• 10 channel bipolar ADC with 32bit resolution
• • 6 channels with -2.5V to +2.5V range
• • 4 channels with -5V to +5V range
• miscellaneous LEDs with user-programmable output enable
• 7 relays
• 4 channel DAC (12bit) with 0 to 2.5V output range and load capability of 20mA
• Sensor excitation current sources from 50uA to 3mA

The shell implementation combines an RPN stack and context with a tree structure that indexes peripherals and related commands.

Some traces of old code are still present and should be cleaned/tidied up in future versions.