This uses the default value that can be passed to getattr to simplify
code that uses it. By choosing an appropriate default value, a separate
call to hasattr can be avoided and in some cases duplicate code can be
avoided.
This applies this trick where possible in wire.py and circle.py.
This commit does not change behavior.
This includes `array`, `base`, `bezcurve`, `block`, `bspline`,
`circle`, `clone`, `dimension`, `draft_annotation`, `draftlink`,
`drawingview`, `ellipse`, `facebinder`, `fillet`, `label`,
`patharray`, `point`, `pointarray`, `polygon`, `rectangle`,
`shape2dview`, `shapestring`, `text`, `wire`, `wwproxy`.
These are added to the `draftobjects` Doxygen group
so that the functions and classes contained in each module
are listed appropriately in the automatically generated
documentation.
