Refactored the put-down code for objects in hand

The put-down sequence now consist of three steps (pre-putdown, putdown, unhand). The actual putdown pose is checked for validity using the motion planner OMPL as the pre-putdown and the unhand should be geometrically covered by that.

Also, several code pieced have been optimized for clarity, code style, line lengths and newlines. Transformations into other coordinate frames are being done where necessary. A rudimentary collision object (cylinder) is used for grasped objects as long as we don't have the correct meshes for the objects at hand.