[Gameplay A24] - Change nisean_horses technology.
Nisean war horses were reserved for the heaviest shock cavalry (i.e. champion spearmen in 0 A.D.).
- Limit to Champion Cavalry Spearmen.
- Increase training time by 10%.
- Food cost raised to 400.
- Made the "Horse Breeding" technology a requirement.
Original patch by: @borg-
Taken over by: @Nescio
Reviewed by: @borg-
Comments by: @Feldfeld, @Palaxin, @ValihrAnt