set current_data.level properly in frametools
Better handle the case where gauges are specified in setrun.py and show up in gauges.data but are not in fort.gauge, perhaps because gauge location is outside domain or initial time of gauge recording was not reached.
Merge branch 'missing_gauges' into levels_gauges

* missing_gauges:
  Better handle the case where gauges are specified in setrun.py and show up in gauges.data but are not in fort.gauge, perhaps because gauge location is outside domain or initial time of gauge recording was not reached.
  set current_data.level properly in frametools
Merge branch 'plotclaw_Agg' into levels_gauges

* plotclaw_Agg:
  set Agg backend in plotclaw.py for some systems where it complains about DISPLAY not being set.
improved warnings printed if gauges.data not found
Merge branch 'master' into levels_gauges
Update to include a merge already incorporated in this branch.

* master:
Merge pull request #101 from rjleveque/levels_gauges

Updates to handle missing gauges better