[SUGGESTION] [EDITOR] One-Way arrows should not be rendered on steel

[Wafflem]

Much like how one-way arrows should not be rendered on objects, one-way arrows should not be displayed on steel pieces either. Steel cannot be destroyed in any way, making the arrows essentially useless.

[namida]

This one may be a bit trickier to fix, especially in regard to manually-placed steel areas, but I'll take a look at it tomorrow.

[namida]

Without some major changes, I can't do much in regards to manually-placed steel areas.

However, for the next update, I've made it not render them on autosteel pieces.