fix for Coords.add()

Author: poke1024

mathics/builtin/graphics.py

@@ -77,7 +77,7 @@ def pos(self):
 
     def add(self, x, y):
         p = (self.p[0] + x, self.p[1] + y)
-        return Coords(self.graphics, pos=p, d=self.d)
+        return Coords(self.graphics, pos=p)
 
 
 class AxisCoords(Coords):
@@ -95,6 +95,9 @@ def pos(self):
         else:
             return p
 
+    def add(self, x, y):
+        raise NotImplementedError
+
 
 def cut(value):
     "Cut values in graphics primitives (not displayed otherwise in SVG)"