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.

I don't think this should be wrapped in a huge `try`/`catch` block. If something goes wrong, the default unhandled-exception handler will be executed and it will print out the error string for us (making the catch down below unnecessary).