demag_gui.py: made new high level pars update and fixed error with switching PCA on selection
demag_gui.py: made new high level pars update and fixed error with switching PCA on selection

Caoimhinmg/PmagPy,lfairchild/PmagPy,lfairchild/PmagPy,Caoimhinmg/PmagPy,Caoimhinmg/PmagPy,lfairchild/PmagPy