The findMidpoint function (used by Draft_Snap_Midpoint) only worked for straight and circular edges. With this revision the midpoint of all edges can be found.
* get_referenced_edges(property_value): returns the Edges referenced by the value of a App:PropertyLink, App::PropertyLinkSub or App::PropertyLinkSubList property.
* get_placement_perpendicular_to_wire(wire): returns the placement whose base is the wire's first vertex and it's z axis aligned to the wire's tangent.
* get_extended_wire(wire, offset_start, offset_end): returns a wire trimmed (negative offset) or extended (positive offset) at its first vertex, last vertex or both ends. For example:
get_extended_wire(wire, -100.0, 0.0) -> returns a copy of the wire with its first 100 mm removed
get_extended_wire(wire, 0.0, 100.0) -> returns a copy of the wire extended by 100 mm after it's last vertex
This includes `arcs`, `circle_inversion`, `circles`, `circles_apollonius`,
`circles_incomplete`, `cuboids`, `edges`, `faces`, `fillets`,
`general`, `geometry`, `intersections`, `linear_geometry`,
`offsets`, `sort_edges`, `wires`.
These are added to the `draftgeoutils` Doxygen group so that
the functions contained in each module are listed appropriately
in the automatically generated documentation.
