It is always implemented exactly the same way (as an uint8) so there is
no reason to implement it in each target separately.
This also makes it easier to add some documentation to it.
- Fix UART & putChar
- Timer-based sleep
- Enable systick in abort
- Buffered, interrupt-based UART TX
- Use the new interrupt API and fix sleepTicks
- Make pins behave more like other boards
- Use the MCU's UART numbering
- Allow interrupts to wake the scheduler (#1214)