- nRF51: Use `uart_conf_t` for consistency with nRF52
- nRF52832: Use UARTE (UART with EasyDMA) over UART (without DMA), as
done for all other nRF52 family members
- use `UARTE_PRESENT` to detect whether an UARTE can be used, rather
than family names
- most were trivial
- missing group close or open
- extra space
- no doxygen comment
- name commad might open an implicit group
this hould also be implicit cosed but does not happen somtimes
- crazy: internal declared groups have to be closed internal
