 ... pk]; then X is split
 into p1*p2*...*pk matricies of dimension d1/p1 x d2/p2 x ... x dk/pk. If
 di/pi is not an integer, floor(di/pi) is used.  Leftover chunks of X are
 discarded. Using a scalar p for parts is equivalent to using [p p ... p].

 So for example if X is 10*16, mat2cell2( X, [2 3] ) breaks X into 2*3
 parts, each of size 5x5, and the last column of X is discarded.

 USAGE
  C = mat2cell2( X, parts )

 INPUTS
  X       - matrix to split
  parts   - see above

 OUTPUTS
  C  