matrix-transpose-arguments

Hi,
changes to matrix_transpose to allow specifying the matrix size on the command line.

using
example/CmakeLists.txt from previous pull-request for program-options.

Why are these in multiples of `1024`? It would be better just to let the user specify what size they actually want. Also, I think it would be more intuitive to name the arguments `"rows"` and `"cols"` (or just `"size"` if the matrix is required to be square).