Entropy flag is a vector for all particle types, but not handled as such.

It seems that when we read the flag_entropy:

readAttribute(h_grp, "Flag_Entropy_ICs", INT, flag_entropy);

we have room for a single int, whereas the stored value is an vector with a value for each particle type. Worked around that and this test now runs. Does this value really need to be a vector?

Issue came up in tests for merge request !203 (merged).