1.9: Publish

As I have reached a stable point in previous step, I create a git repository stm32bringup, publish it on github.com with a mirror on git.sdf.org.

I chose MIT license as open source license for the code.

The only rework of the C sources is the addition of a copyright notice and conversion of tabs to spaces for portability.

Next I will start working with USART peripherals: select an USB adapter, flash the board over the UART communication and say hello to the world.