Merge branch 'side-springs' into 'master'

Sideways springs, horizontal hog-launchers, perpendicular plungers...

Call them what you like, they're in the code now. And have been for months!

Nev3r uses the hell out of these and I'm fed up of them being <!>'s all over the place, so please have 'em in master so we can update srb2.srb and make things better for all of us.

See merge request !30