add width, height

but not used

Signed-off-by: Michael Leuschel <leuschel@uni-duesseldorf.de>

Jars/DieHard_tla.json

 {
   "svg":"Jars.svg",
+  "svg_box": {"height":200, "width":360},
   "comment": "VisB Visualization for Jars by Jonas Erdmann",
   "definitions":[
     {"name":"level",