allow to set a Gmsh option just by using its name (same as was done for...

allow to set a Gmsh option just by using its name (same as was done for getting Gmsh options). This allows to simply use e.g.

SetNumber["Geometry.Points", 0];

in GetDP to configure Gmsh. (The old way, i.e., using the "GmshOption" attribute still works, but only triggers option changes when an action is undertaken in the gui)