* normalize MPI communicator handling by putting some default
  code in DataAdaptor and AnalysisAdaptor base classes. The
  defaults are to use isolate our communciation in a duplicate
  of COMM_WORLD. Adaptors needing to do MPI communicaiton should
  access the communicator by calling GetCommunicator.
* report errors from ConfigurableAnalysis::Execute and ::Finalize
* fix a build issue with new VTK AMR writer.
* clean up warning in parallel 3d miniapp

squash me -- amr reader build fixes"