Draft: fix mismatch of argument in get_dxf function

The name of the argument, `projection`, in the old function
is incorrect; it should be `direction`, which was the original
argument's name when this method was split into its own module
(c79f890).

src/Mod/Draft/draftfunctions/dxf.py

@@ -134,10 +134,10 @@ def get_dxf(obj, direction=None):
 
 
 def getDXF(obj,
-           projection=None):
+           direction=None):
     """Return DXF string of the object. DEPRECATED. Use 'get_dxf'."""
     utils.use_instead("get_dxf")
     return get_dxf(obj,
-                   projection=projection)
+                   direction=direction)
 
 ## @}