Use Truchas FIELDNAME attributes as the displayed field name
This is a fix for an issue over at the Truchas repo (see here). In short: we'd like Truchas data fields to have a Paraview display name set by the FIELDNAME attribute in our HDF5 file, and VOF components named by the attributes "FIELDNAME1", "FIELDNAME2", etc. For example, the display name for the "Z_RHO" dataset should be "Density" (the "FIELDNAME" attribute for "Z_RHO"). Likewise, VOF components should be given a nice name from attributes we set in Truchas, rather than a number.