This brings in the new ADC api for STM32 parts. Update to new standardized ADC apis. Drops pointless channel definitions, uses common names for common functions. No functional changes. Based on work in: https://github.com/libopencm3/libopencm3-examples/pull/130
README
This example program sends some characters on USART1. Afterwards it read out the internal temperature sensor of the STM32 and sends the value read out from the ADC to the USART1.
The terminal settings for the receiving device/PC are 115200 8n1.