remove import math from ipmag and replace math.pi with np.pi
remove import math from ipmag and replace math.pi with np.pi

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