set up an automated clang-tidy test

[punytroll]

Calling clang-tidy is dependent upon the compiler_commands.json that can be generated with the tool bear. This needs to be set up first.
Secondly an automated run over all cpp files can be set up.
The set of checks to perform needs to be investigated thoroughly and an explanation file for the selection can go into documentation.

[punytroll]

Instead of depending on bear, I could also write a python tool that turns the output of
$> make --always-make --keep-going --dry-run --print-directory
into the compiler_commands.json.