converted the project into a PlatformIO project

[FiveTeethless]

• I have moved all source files into a new PlatformIO project.
• The .ino file is still there, so it can be used for simulation in Wokwi.
• The git submodules have been removed in favor of the library definition within the platformio.ini file.
• the libraries.txt for Wokwi now also contains fixed libary versions

Questions:

1. We could still use git submodules if this is the favored option. there is a "lib" directory with PlatformIO projects. Should we go back to git submodules?
2. I changed the name of the actual PIO project to end with "-pio". This is actually not necessary. How to go on?

solves #1