currently, when follow mode is changed to free spectation mode, the camera of the spectator moves away (depending on the viewheight of the followed player), and turns into a not well-defined direction.
also, the speed of the followed player is inherited.
Created attachment 2843 [details] when stopping follow mode, keep the view origin and direction, and stop
the function in bug 5085 is required.
this patch also depends on the patch in bug 5005.
Created attachment 2843 [details] when stopping follow mode, keep the view origin and direction, and stop