Initial import of low-level timer driver interface

Fixed spelling

drivers: adjustments to low-level timer driver IF

drivers: added [in|out] to @param documentation

drivers: fixed doxygen for tim_t typedef
Merge pull request #614 from haukepetersen/periph_driver_timer

Initial import of low-level timer driver interface
drivers: Initial import of low-level UART driver interface

Fixed spelling

drivers: remodeled low-level uart driver interface

- added blocking mode of operation
- added UNDEFINED device for compatibility
- changed baudrate type to uint32_t

drivers: added [in|out] to param documentation
Merge pull request #613 from haukepetersen/periph_driver_uart

Initial import of low-level UART driver interface
drivers: Initial import of low-level ADC driver interface

Fixed tons of spelling errors

Fixed typo in ADC_NUMOF macro

drivers: adjustment to low-level adc drvier IF

drivers: added [in|out] to doxygen @param comments
Merge pull request #616 from haukepetersen/periph_driver_adc

Initial import of low-level ADC driver interface