Further fixed and enhanced grasping and putdown code

Evaluation of possible grasps is now *much* faster. Also, the code for putting down objects is now a) much shorter, and b) also works with grasp poses that are not axis-aligned (this was a problem in the past with certain grasp poses).
Added automated pose elevation for putdown poses

This helps to avoid the collision environment spoiling put-down due to collision between an object and the surface it is to be put down on.