Adds a support rail object.

The support rail lets you grab it, sort of like buckling into a chair,
that gives your shoes noslip. Useful for ZAS areas like airlocks. Also
includes icon.
No THIS one has the icons.
Fixes a really dumb overlap from my work on another commit
I made my mistakes. Got nowhere to run. But life goes on as I'm fading
away.
Editing.
Typecasting issue resolved#
another minor fix
Merge pull request #1954 from Kurfursten/supportrail

Adds a support rail object.