Initial support for stm32f3. Changes in makefiles, gpio.

- Makefiles now include building f3 src directory.
- Gpio support added. gpio_common_f24 changed to support also f3.
- f3 still not compiling, but f2 compile not broken (probably also f4).
linker script file for f3 added.
Memory map for f3 added.
Fixed compile of f4 and l1 after gpio_common_f234.c renaming.
Makefile for f3 lib added. Gpio.c and rcc.c also in.
Added interrupts for f3, Pre_main rutine in vector_chipset, nvic.h modified to include f3.
general gpio for stm32 modified to include f3
pwr headers added. Now f3 support compiles
Fixed compile warning, function declaration in rcc.h wrong
F3 missing headers added.
Partial flash support added.
Unnecessary include of pwr.h removed from rcc.c. Pwr.h becomes unnecessary to run the f3
i2c support added.

Most of the changes went to i2c_common_all.h file.
F3 is considerably different than all the other in i2c.
Adc stm32f3 support added.
Missing files for adc stm32f3 support added.
stm32f3 dac support added.
Fixed missing gpio F port stm32f3.
stm32f3: adding external interrupts support.
Stm32f3: usart support added.
stm32f3: Crc support added.