calc_nway_interaction.m
'calc_nway_interaction(anovadata,nrofsubjects,validfactor,n)'
calculates n-way-interaction for the data given in anovadata.
the number of rows in anovadata corresponds the number of
subjects. 'factor' is a cell containing the name of the factors
in the first column and the number of gradations in the second
column. 'n' specifies the order of the interactions to be
calculated. Factors must be in hierarchical order, starting
from the highest level.