Separate ambient light and solar panel efficiency (#1593)

* new branch

* Separate ambient light and solar panel efficiency

* Made ambient light -> solar efficiency default

core/src/mindustry/game/Rules.java

@@ -82,6 +82,9 @@ public class Rules{
     public boolean lighting = false;
     /** Ambient light color, used when lighting is enabled. */
     public Color ambientLight = new Color(0.01f, 0.01f, 0.04f, 0.99f);
+    /** Multiplier for solar panel power output.
+    negative = use ambient light if lighting is enabled. */
+    public float solarPowerMultiplier = -1f;
     /** team of the player by default */
     public Team defaultTeam = Team.sharded;
     /** team of the enemy in waves/sectors */