Replaced Teuchos_StandardUnitTestMain with Teuchos_StandardParallelUnitTestMain, to allow parallel tests with parallel reductions.
Renamed getNeighbor() to getNeighborInfo() and added a getNeighbor() method that returns a CellPtr, and getNeighbors() that returns all non-null neighbors.
Added support for static condensation.
Refactored OverlappingRowMatrix, primarily to allow easier testing.
Added OverlappingRowMatrixTests.  Both tests pass (tested with 1,2,4,16 MPI ranks).