[FEATURE] Render slope previews in 3d mode for Odamex

[Xenaero]

Linedef actions 340-347 which seem to be specific to the multiplayer source port Odamex operate in similar way to the much-familiar plane align action, but do not render in the 3d mode preview. These actions currently only exist in the Odamex Doom in Doom config, but may also work in the Doom in Hexen side as well.

As I do not believe official Odamex configs exist for UDB, I have some frankensteined configs that some of us in the Odamex community have been using up to this point that I'm attaching here for your testing. Those configs may need some tweaking and input from the Odamex devs before inclusion into UDB proper.

Odamex UDB Configs.zip .