mean.m: Accept large DIM inputs and calculate Matlab-compatible output (bug #63411) * mean.m: Accept large DIM inputs by removing any dimensions larger than the dimensions of the input array. Use vectorized operations, rather than for loop, for this input validation. Pre-declare output array before for loop for performance. Use ipermute() after calculations to return correctly-dimensioned result (checked with Matlab). Change BIST tests results to match correct behavior.