writeSVGMatrix parameters are inconsistent with other IO writers

Other IO writers have the std::ostream parameter first and the container second. writeSVGMatrix takes the container first and the std::ostream second. For example:

printvector(std::cout, x, "foo", "faa");
writeSVGMatrix(mat, std::cout); // arguments are swapped

This could easily be fixed with another overload while deprecating the other use.