Better method of reset and clock handling with RCC, support L1, F1, F2, F4

Better names for the reset and clock handling with RCC, for F2xx and F4xx
Added doxygen for the RCC module, formatted to linux coding style

Added clock setting capability for F1 and L1

Merge branch 'clock_enable' of https://github.com/BuFran/libopencm3 into clock_enable

Conflicts:
	lib/stm32/f2/Makefile
	lib/stm32/f4/Makefile

Removed the macro expansion versions of reset control