Add: HeartManager, HeartGauge

src/game/lib/heart_gauge.js

@@ -0,0 +1,22 @@
+class HeartGauge {
+
+	constructor(heartManager) {
+		this.heartManager = heartManager;
+
+		this.heartManager.addOnChangeHeartListener(
+			() => {
+				console.log(this.heartManager.getHearts());
+			}
+		);
+	};
+
+}
+
+HeartGauge.DEFAULT_TEXT_FONT = {
+	font: "30px Arial",
+	boundsAlignH: "center",		// left, center. right
+	boundsAlignV: "middle", 	// top, middle, bottom
+	fill: "#fff"
+};
+
+HeartGauge.MOVE_UP_AMOUNT_PX				= 50;