use inner interface instead of default impl so we can go back to java 7 :) (close #87)

src/yugecin/opsudance/Dancer.java

@@ -160,7 +160,7 @@ public class Dancer {
 		}
 		this.moverFactoryIndex = moverFactoryIndex;
 		moverFactory = moverFactories[moverFactoryIndex];
-		multipoint = moverFactory.isMultiPoint();
+		multipoint = moverFactory instanceof MoverFactory.MultiPoint;
 		// to prevent crashes when changing mover in storyboard, create mover now
 		createNewMover();
 	}

src/yugecin/opsudance/movers/factories/MoverFactory.java

@@ -24,8 +24,8 @@ public interface MoverFactory {
 
 	Mover create(GameObject start, GameObject end, int dir);
 
-	default boolean isMultiPoint() {
-		return false;
+	interface MultiPoint {
+
 	}
 
 }