Implement new application logic and new API logic

main.c should now include only application code and all other files
should be application independent framework code.

All APIs (ADC, Temperature, Gyro) may run in their own threads
reading new data periodically. When new data is available, an event
is passed through the event loop to the application. Application can
then get the new data from the API.

Add ADC API as a reference API implementing the new API logic.
Makefile: ChibiOS merged F2 platform code to F4
adc: Fix fatals bugs

Fixes to get ADC actually working.
event: Handle adc and temp available events.
main: Print ADC to UART periodically.
main: Report ADC pin1 in cm.
sdu: Add circular send buffer.

Handle several subsequent send message calls without data loss by
adding a circular buffer.
main: Handle three ADC pins.

Read sonar, current consumption and battery voltage on first three
ADC pins and do the conversion to human readable format.