Objects falling to floor: 2 cases

[rojas70]

In branch picking_environment_new_reset we introduced a new reset formulation where we do soft resets after 1 object is picked up and hard resets when all objects or ill conditions appear.

Objects may fall in two situations:

1. #model==#load
   In cases, where the number of objects loaded is equal to the number of objects modeled, objects fall only from bin2, when a new object is placed unto bin2. This does not occur because that new object falls on top of the previous model, it must be related to the way the position of the objects is maintained across resets.

2. #model<#load
   In cases, where the number of modeled objects is less than the loaded number of objects, the objects tend to fall down while doing a regular pick in bin1.

There must be some problem in the way the position of an object is updated when it is the list of "self.not_yet_considered_objects"... Need to dig in here.