Add initial support for HDF5 ATTRIBUTEs

Add initial (limited) support for HDF5 ATTRIBUTEs. The support is focused on the output of HDF5 files compatible with QuantumESPRESSO HDF5 wave functions files.

Current limitations:

ATTRIBUTEs can only be added to the current GROUP or in a DATASET belonging to the current group
ATTRIBUTE's DATASCPACE is assumed to be HD5_SCALAR
Reading ATTRIBUTEs is not implemented

HDF5 file produced by test4:

HDF5 "qe.h5" {
GROUP "/" {
   ATTRIBUTE "gamma_only" {
      DATATYPE  H5T_STRING {
         STRSIZE 7;
         STRPAD H5T_STR_SPACEPAD;
         CSET H5T_CSET_ASCII;
         CTYPE H5T_C_S1;
      }
      DATASPACE  SCALAR
      DATA {
      (0): ".FALSE."
      }
   }
   ATTRIBUTE "igwx" {
      DATATYPE  H5T_STD_I32LE
      DATASPACE  SCALAR
      DATA {
      (0): 4572
      }
   }
   ATTRIBUTE "scale_factor" {
      DATATYPE  H5T_IEEE_F64LE
      DATASPACE  SCALAR
      DATA {
      (0): 1
      }
   }
   ATTRIBUTE "xk" {
      DATATYPE  H5T_ARRAY { [3] H5T_IEEE_F64LE }
      DATASPACE  SCALAR
      DATA {
      (0): [ 0, 0.13, 0.1 ]
      }
   }
   DATASET "MillerIndices" {
      DATATYPE  H5T_STD_I32LE
      DATASPACE  SIMPLE { ( 3, 2 ) / ( 3, 2 ) }
      DATA {
      (0,0): 0, 0,
      (1,0): 0, 0,
      (2,0): 0, 0
      }
      ATTRIBUTE "bg1" {
         DATATYPE  H5T_ARRAY { [3] H5T_IEEE_F64LE }
         DATASPACE  SCALAR
         DATA {
         (0): [ 0.67, 0.39, 0 ]
         }
      }
      ATTRIBUTE "doc" {
         DATATYPE  H5T_STRING {
            STRSIZE 34;
            STRPAD H5T_STR_SPACEPAD;
            CSET H5T_CSET_ASCII;
            CTYPE H5T_C_S1;
         }
         DATASPACE  SCALAR
         DATA {
         (0): "Miller Indices of the wave-vectors"
         }
      }
   }
   DATASET "evc" {
      DATATYPE  H5T_IEEE_F64LE
      DATASPACE  SIMPLE { ( 4, 3 ) / ( 4, 3 ) }
      DATA {
      (0,0): 0, 0, 0,
      (1,0): 0, 0, 0,
      (2,0): 0, 0, 0,
      (3,0): 0, 0, 0
      }
      ATTRIBUTE "doc" {
         DATATYPE  H5T_STRING {
            STRSIZE 28;
            STRPAD H5T_STR_SPACEPAD;
            CSET H5T_CSET_ASCII;
            CTYPE H5T_C_S1;
         }
         DATASPACE  SCALAR
         DATA {
         (0): "Wave Functions, (npwx, nbnd)"
         }
      }
   }
}
}

(Compare with QuantumESPRESSO HDF5 wave functions files)

electronic-structure / SIRIUS

Add initial support for HDF5 ATTRIBUTEs #872