Merge pull request #112 from it-workshop/wp/CAROLINE-36/1

CAROLINE-36: Remove position_controller.
(cherry picked from commit 2c032a38a2e3e18c53e8340158d5a979947e578c)

Conflicts:
	core/position_controller.cc
	core/position_controller.h
	core/predefined_position_controller.cc
	core/predefined_position_controller.h
	core/undefined_position_controller.cc
	core/undefined_position_controller.h