Add bbox property to Abstract.Multi

It returns the bounding box of the multi object

Author: orbingol

geomdl/Abstract.py

@@ -1438,6 +1438,17 @@ def evalpts(self):
             ret.append(evalpts)
         return ret
 
+    @property
+    def bbox(self):
+        """ Bounding box.
+
+        :getter: Gets the bounding box of all contained shapes
+        """
+        all_box = []
+        for elem in self._elements:
+            all_box += list(elem.bbox)
+        return utilities.evaluate_bounding_box(all_box)
+
     @property
     def vis(self):
         """ Visualization component.