Added ADS111X ADC as analog source

[Ultrawipf]

This adds basic support for the ADS1115 I²C ADC as an analog source

The address is fixed to the primary address when ADDR is connected to GND (default on most modules if ADDR is left open)

The user can select:

• Number of inputs (1-4 or 1-2 in differential mode)
• Differential mode or single ended
• Gain from 2/3 to 16x
• Sample rate from 8sps to 860sps (I would not recommend going below 128sps...)