Updated the documentation so that it appears in all families
Also added it to the L1 area, but is untested. An addition to the memorymap
allows commonality and a #ifdef added to the spi_common_all code to
exclude the case of SPI3 for L1 and F0 as SPI3 doesn't exist in those.
An rcc dispatch header was added to remove same code from the spi header.
All #includes now explicitly use the "<libopencm3/stm32/rcc.h>" format.
If you want to get rid of the "libopencm3" prefix in your local project you
can add a respective -I entry in your Makefile (not recommended though).
All .ld files and .a libs are installed in $(TOOLCHAIN_DIR)/lib
directly (as before), but are now renamed to avoid potential
conflicts now or in the future. Examples:
libopencm3_lpc13xx.a
libopencm3_lpc13xx.ld
libopencm3_stm32.a
libopencm3_stm32.ld
