Add average wheels diameter (perimeter)

Measured perimeter of the right wheel : 176
Measured perimeter of the left wheel : 177
Average perimeter : 176.5
Fixed mistake in comments
Non-working square run
Merge remote-tracking branch 'origin/developer' into localization-calibration
Little tests
Merge branch developper
Merge remote-tracking branch 'origin/developer' into localization-calibration
Functions to know when a movement is ended
Add a useless action if there is nothing to display

Apparently a task cannot be empty. So display task cannot be empty, even
if there is nothing to display.
Revert tests from localization-calibration