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 is the smallest-possible example program using libopencm3.
It's intended for the ST STM32F3DISCOVERY eval board. It should read from the
ADC1_IN1 (PA0) pin its voltage and print it in the LEDs.