added Visio stencil

Created by: sixdiamants

vsg shapes were imported into Visio and then redrawn as accurately as possible. Arrow-heads and linestyles may differ ever so slightly. Some symbols were regrouped into a single master and the user can select the type of incarnation. See the example of the train in the picture.

Merged by: kaat0 at 2022-01-27 17:51:52 UTC