Splined is the path editor for Raid'em.  It is written very crappily,
so be warned.  Anyway, the controls are:

   hjkl			Pan
   Q			Quit
   Spacebar		Toggle grid snap
   Up/down		Increase/decrease path length
   Ctrl-L		Load spline
   Ctrl-S		Save spline
   LMB			Add/move a control point
   Ctrl + LMB		Orthogonal movement
   Shift + LMB		Move only one control point
   RMB			Remove a control point
