Some more file/path restructuring.

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

examples/stm32/other/timer_interrupt/timer.c

@@ -17,11 +17,11 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-#include <stm32/rcc.h>
-#include <stm32/flash.h>
-#include <stm32/gpio.h>
-#include <stm32/timer.h>
-#include <stm32/nvic.h>
+#include <libopencm3/stm32/rcc.h>
+#include <libopencm3/stm32/flash.h>
+#include <libopencm3/stm32/gpio.h>
+#include <libopencm3/stm32/timer.h>
+#include <libopencm3/stm32/nvic.h>
 
 void gpio_setup(void)
 {