Since BBT was implemented there was a lot of dead code in the repo. Note
that method setRobotPositions was not removed yet. Removing it
causes linking issues (wtf?)

- Since old collision detector is removed, world objects can be renamed to collision detector
  (a way better name imho)
- Collision Detector now precomputes the positions of all robots at the start of each tick,
  to (theoretically) save time when performing collision checks (lookup vs computation)

Next the Position Control has to be refactored!

There are 2 main reasons for this change:
1) The previous path planning was slow
2) The previous implementation was spaghetti

The new implementation speeds up the position control significantly (60 ticks per second with -0g)

All the details are recorded in docstrings, but main idea of the new implementation was to separate
better separate concerts(path tracking x path planning x position control). For example path tracking
is now stateful and there is instance for each robot separately.

Small change to remove unnecessary variable