pvbatch warnings if directory missing are confusing
If the directory that pvbatch is trying to write to is missing, the warning message is way confusing. A user just tried to debug this:
^[[0m^[[31m( 7.161s) [main thread ] vtkImageWriter.cxx:509 ERR| vtkPNGWriter (0xc89d520): Ran out of disk space; deleting file(s) already written^[[0m
^[[0m^[[31m( 7.410s) [main thread ] vtkPNGWriter.cxx:253 ERR| vtkPNGWriter (0xfb61b70): Unable to open file ../output/quench_avg_eqps.15.png^[[0m
^[[0m^[[31m( 7.410s) [main thread ] vtkImageWriter.cxx:509 ERR| vtkPNGWriter (0xfb61b70): Ran out of disk space; deleting file(s) already written^[[0m
^[[0m^[[31m( 7.843s) [main thread ] vtkPNGWriter.cxx:253 ERR| vtkPNGWriter (0xf843820): Unable to open file ../output/quench_avg_eqps.16.png^[[0m
Please change the code to TEST if the directory exists, and give a warning appropriately. If the file can't be written, then say something like "File can't be written. Possible issues are permission issues or the disk is full".