GEOMESA-101 Optimize geometry only queries in iterator

Adds an iterator that runs in place of both the SpatioTemporalIntersectingIterator and the SimpleFeatureFilteringIterator.  This iterator is used in special situations where the ECQL query can be fully re-written in terms of a polygon and interval AND a transform is defined that only selects the index attributes. 
  
I suspect there might be a way to use a for-comprehension to make this slightly easier to read, but it's hardly worth the effort (except for the fun of it).  This might be along some of the lines of what John is going to talk about Monday at lunch.