demag_gui.py: fixed export error where certain coordinate systems and only those would be exported regardless of check box.
demag_gui.py: fixed export error where certain coordinate systems and only those would be exported regardless of check box.

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