Remove FORWARD_S and BACKWARD_S from input state.

Remove FORWARD_S and BACKWARD_S from input state.

The input core does separate playing states for forward or backward direction from the playing state PLAYING_S. If one wants to know in what direction VLC is playing, then he needs to look at the sign value of the "rate" value. Backward playing direction has a negative "rate" value. Forward playing direction has a positive one.