Set of fixes that *hopefully* address a number of potential stack trace errors.  These
fixes include
o changes to the MInLongHeap that check for the case whn a heap is newly created
  and there is only one element, but not the one we're looking for.
o Similarly, changes to RTree.exists to return false if we run off the end of the array
o Changes to RowSetViewUpdater (and friends) that only update the relevant node or edge
  style and not the entire network.
o Changes to DGraphView and DEdgeDetails to catch some exceptions and manage them better

Refs #2843, Refs #2842, Refs #2853

These fixes don't necessarily solve all of the above bugs, but the incidence should be
significantly reduced.

Change-Id: I5e45099766055856bfc65adac2d8bc86f9ce2ec0