Added keyword dim to frontend function for spectrum.read_spins().
Work in progress for Support Request #3044, (https://gna.org/support/index.php?3044) - Load spins from SPARKY list.
This is associate data with the spins of up to two dimensions.
Authored by: tlinnet 2013-12-06
Parent: [r21804]
Child: [r21806]
