auto_link.py

Define the auto link policies between different waveguide type.

For example:

(type(WG.SusSi.MWIR.WIRE) >> type(WG.SusSi.MWIR.WIRE), StraightPrefer(WG.SusSi.MWIR.WIRE), BendUsing(WG.SusSi.MWIR.WIRE.BEND_EULER))

It means that when the start and end waveguide are both WG.SusSi.MWIR.WIRE, the automated waveguide type for routing will be WG.SusSi.MWIR.WIRE and an automated bend WG.SusSi.MWIR.WIRE.BEND_EULER will be added at a 90 degree turn.

Users are allowed to define and set DEFAULT to their own specific linking policy.