REL-2063: QPT cannot open existing queue plans.

Don't create Alloc objects for observations that can not be found in the ODB data provided by the mini model. This can for example happen if an observation is deleted or its state is changed from Prepared to Inactive (or in many other cases). This case was silently tolerated in earlier QPT versions where the obs object was not part of the hashCode, compareTo and equals methods which changed with PR-8 https://github.com/gemini-hlsw/ocs/pull/8. What happened was that Alloc objects were created but (I think) never really showed up anywhere and probably were lost / filtered out at some point. Now Alloc objects are only created if a corresponding obs is found in the mini model data. All other observations are ignored and will (as previously) not show up on the plan. I spoke with a QC here and this is the expected behavior, so I think were good with this.