Add path interface

[ll-nick]

Closes #20

This PR changes the Direction in the command struct to a Path allowing more complex behaviors.

I built this on top of https://github.com/KIT-MRT/arbitration_graphs/pull/19 since that one would have to be adjusted too. So let's merge #19 first, then this PR becomes a little more obvious.

I've snuck in two more commits:

• 04ba976ab9ff1f948999e0f113ab9c85d865b454 Fixes some linter warnings that pop up since I fixed the clang-tidy config
• c835f8f1c6da446cb914637036e479ba1f34b280 Renames the distance function to manhattanDistance to avoid confusion with the euclidean distance which still exists as a member function of the position struct

[orzechow]

Btw. I changed the base to the random walk branch, in order to review only the new commits here. Changed it back to demo again