Refactored AEConfig (#2633)

Added a singleton getter instead the public field.
Reduced all fields to private.
Replaced field access with getters.
Added setters where necessary (Dimension/Biome Registration)
Added config options to disable more features.
Splitted Enum name from the config key.
Changed FacadeConfig and Networkhandler similar to AEConfig.init().

src/main/java/appeng/entity/EntitySingularity.java

@@ -74,7 +74,7 @@ public final class EntitySingularity extends AEBaseEntityItem
 			return;
 		}
 
-		if( !AEConfig.instance.isFeatureEnabled( AEFeature.InWorldSingularity ) )
+		if( !AEConfig.instance().isFeatureEnabled( AEFeature.IN_WORLD_SINGULARITY ) )
 		{
 			return;
 		}