Add Support for QElement Rectangle Types

[Vadoola]

DXF Has no rectangle types that I'm aware of, but QElectrotech does. I already do some work to convert 2 point splines, polylines etc to QET Line elements. Could I add support for the QET Rectangle Element, by looking for 4 Point Polylines that are closed, and then check to see if they are rectangles? Might simplify some resulting elements.