[feature] Support for ITM trace port (printf style debugging)

[Slamy]

This project is great but there is still no possibilty to acccess the ITM trace port under linux. Is this planned? I could only find st-term which tries to handle this in a different way.
I'm trying to hack this myself into your code but I don't know where to start as I couldn't find a lot of the needed magic numbers inside the debug documtentation of the stm32f4.

[SuperVirus]

Hi, i started working on this feature a few weeks ago.

Someone else has done some work on this, too: https://github.com/obe1line/stlink-trace
Maybe this a good starting point for you.

BTW.:
The necessary documentation is spread around some documents at ARM.

[xor-gate]

Duplicate of #136