Move AUDIT_DATASET to coreCIF

[vaitkus]

The AUDIT_DATASET category seems to be applicable outside of the multiblock approach used for the representation of complex data. For example, if I understand the example correctly, this approach could be used to link the calibration data block to the measurements of several regular crystals that follow it.

As such, it might make sense to move it to the coreCIF dictionary that is imported by MultiBlock dictionary either way.