XDMF Writer Produces Incorrect Array Shapes

[davschneller]

For the group and boundary arrays; they get prepended by a dummy dimension; causing SeisSol to fail (without patches).

Cf.

GROUP "/" {
   DATASET "boundary" {
      DATATYPE  H5T_STD_I32LE
      DATASPACE  SIMPLE { ( 1, 845815304 ) / ( 1, 845815304 ) }
   }
   DATASET "connect" {
      DATATYPE  H5T_STD_I64LE
      DATASPACE  SIMPLE { ( 845815304, 4 ) / ( 845815304, 4 ) }
   }
   DATASET "geometry" {
      DATATYPE  H5T_IEEE_F64LE
      DATASPACE  SIMPLE { ( 151910582, 3 ) / ( 151910582, 3 ) }
   }
   DATASET "group" {
      DATATYPE  H5T_STD_I32LE
      DATASPACE  SIMPLE { ( 1, 845815304 ) / ( 1, 845815304 ) }
   }
}