Repair to documentation (most documented files)

to remove errors, duplications and inconsistencies.
File lib/stm32/f1/pwr.c - all code removed as it duplicates that in common/pwr_common.c
Remaining changes do not affect code. Compiles OK.
TODO efm32 has no code so generates no modules
TODO F2 needs pwr.c
TODO L1 needs dma.h and dma.c

lib/stm32/f4/rtc.c

@@ -4,6 +4,11 @@
 
 @brief <b>libopencm3 STM32F4xx RTC</b>
 
+@version 1.0.0
+
+@date 4 March 2013
+
+LGPL License Terms @ref lgpl_license
 */
 
 /*