add ipmag fisher_mean function that accepts list of dec and list of inc instead of di_block
add ipmag fisher_mean function that accepts list of dec and list of inc instead of di_block

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