Coordinate pair ordering

A large number of Gandalf routines require horizontal and vertical sizes or coordinates to be passed as arguments, whether representing the dimensions of a matrix or coordinates of a pixel in an image. The ordering of the arguments in such cases is problematic. For specifying a matrix element the most natural ordering is to have the row coordinate first, corresponding to the coordinate order $i,j$ for matrix element $A_{ij}$. On the contrary, for image coordinates there is no obvious convention. In Gandalf a universal convention is applied that in all such cases the vertical or row coordinate is the first argument.