Perform a repeated measures analysis of variance (Repeated ANOVA). X is formated such that each row is a subject and each column is a condition.
condition is typically a point in time, say t=1 then t=2, etc condition can also be thought of as groups.
The optional flag can be either 'cell' or 'string' and reflects the format of the table returned. Cell is the default.
NaNs are ignored using nanmean and nanstd.
This fuction does not currently support multiple columns of the same condition!