Add Clock.tickCount.

src/echoes/utils/Clock.hx

@@ -66,6 +66,11 @@ class Clock {
 	 */
 	public var paused:Bool = false;
 
+	/**
+	 * How many times this clock ticked since the last call to `addTime()`.
+	 */
+	public var tickCount:Int = 0;
+
 	/**
 	 * The amount of time left on the `Clock`, in seconds.
 	 * 
@@ -90,6 +95,8 @@ class Clock {
 			if(this.time > maxTime) {
 				this.time = maxTime;
 			}
+
+			tickCount = 0;
 		}
 	}
 
@@ -100,6 +107,7 @@ class Clock {
 	public function next():Float {
 		var tick:Float = time > maxTickLength ? maxTickLength : time;
 		time -= tick;
+		tickCount++;
 		return tick;
 	}