- 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
- Moved code for periph_conf of all ATmega based boards to boards/common/atmega
- Added possibility to override config from individual board:
- Named file `periph_conf_atmega_common.h` and let this be included from
`board/$BOARD/include/periph_conf.h` to allow modifications
- Guarded individual periph configs by `#ifndef $PERIPH_NUMOF` ... `#endif`