Add closest edgelengths to fit cuboid and rectangle

[Jmariambbu]

Previously, the meshrectangle, meshcuboid and tetmeshcuboid functions changed the geometry to fit to the multiples of a specified edgelength. There was however, a bug that gave an incorrect geometry, in the case of dimensions of the geometry not being multiples of the edgelength. The functions are now changed to produce the geometry with the specified dimensions, and readjust (multiple, if need be) edgelength(s) to fit the specified length, breadth (and height, in cuboid). These edgelengths are picked to be factors of the dimensions of the geometry, that are closest to the specified edgelength.