Contours: Rotate loop along plane

[jlampel]

In v3, the hotkey R was used to rotate the selected loop along its plane, essentially a twist. This was really helpful for making sure verts line up nicely.

In v4, we should leave R to be Blender's usual rotate but have the twist be mapped to Alt R. It would also be nice to be able to quickly adjust this right after inserting, so having twist as a property that can be adjusted in the redo panel afterwards and scrolled with Shift Scroll would be a nice bonus if possible.