Allow for core incineration via rules (#4242)

core/src/mindustry/game/Rules.java

@@ -97,6 +97,8 @@ public class Rules{
     public Team waveTeam = Team.crux;
     /** name of the custom mode that this ruleset describes, or null. */
     public @Nullable String modeName;
+    /** Whether cores incinerate items when full, just like in the campaign. */
+    public boolean coreIncinerates = false;
     /** special tags for additional info. */
     public StringMap tags = new StringMap();