Allow custom lens decals for a particular creature model

[benlp91]

I'd like to be able to have a visor-effect like shown below.

[Loobinex]

Well, lenses are functional. But you want to add a visor type lens, which is not available at the moment.

[xtremeqg]

Reworded title, description to be more descriptive of what is being requested.

[xtremeqg]

I think declaring a new lens kind/type and reusing part of the existing swipe code could work here.