Model IJK index not compatible with Datamine

[opengeostat]

IJK index in PyGSLIB is compatible with GSLIB order (first X, then Y, and finally Z), for example, equal to the row number in a GSLIB grid file. See function pygslib.blockmodel.ind2ijk()... ijk = iz*nx*ny+ iy*nx + ix

Datamine files have a different IJK (first Z, then Y, and finally X)

TODO:
a) add a function to calculate Datamine IJK index.
b) add functions to convert: (1) from Datamine IJK to GSLIB IJK and (2) from GSLIB IJK to Datamine IJK