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/common/gpio_common_f24.c

@@ -1,12 +1,8 @@
 /** @addtogroup gpio_file
 
-@version 1.0.0
-
 @author @htmlonly &copy; @endhtmlonly 2009 Uwe Hermann <uwe@hermann-uwe.de>
 @author @htmlonly &copy; @endhtmlonly 2012 Ken Sarkies <ksarkies@internode.on.net>
 
-@date 18 August 2012
-
 Each I/O port has 16 individually configurable bits. Many I/O pins share GPIO
 functionality with a number of alternate functions and must be configured to the
 alternate function mode if these are to be accessed. A feature is available to
@@ -50,7 +46,6 @@ Example 2: Digital input on port C12 with pullup
 	reg16 = gpio_port_read(GPIOC);
 @endcode
 
-LGPL License Terms @ref lgpl_license
 */
 /*
  * This file is part of the libopencm3 project.