[En-Nut-Discussion] STM32 Rework

[Uwe Bonnes]

Hello,

I just upload a big chunk of patches for Stm32.

Important user visible changes are:
- Only use part designator in the .conf file, like
  MCU_STM32L476xG = ""
  No more need to list family/subfamily and linker file in
  the conf file.
- Device pins now carry full information, like
  USART2_TX = "PD05"
- Stm32 Configuration items hopefully cleaned up a little and arranged
  more logical.
- (Basic) Configuration for most Stm32 Discovery and Nucleo boards
  in trunk.

Behind the scene:
- Support for STM32F7, STM32L4 and STM32L0 families added.
- Use the StCubeMX headers.

Newer files and changes in this chunk should follow the NutOs style guide
more closely.

Please let me know if you find any problems!

Cheers!
-- 
Uwe Bonnes                bon at elektron.ikp.physik.tu-darmstadt.de

Institut fuer Kernphysik  Schlossgartenstrasse 9  64289 Darmstadt
--------- Tel. 06151 162516 -------- Fax. 06151 164321 ----------