Scale issues on multiple clicks

[Steve-Parker]

Hi - awesome control. 谢谢!!

I found a bug where if the user presses repeatedly on the MenuButton - the block for completion ends but the start animation is still firing which means when you next see the icons, the one you clicked has an incorrect scale.

I fixed this by putting the line in bold in the touchesBegan code...

• (void)touchesBegan:(NSSet _)touches withEvent:(UIEvent )event {
  // 播放缩放动画
  //-- Stop touches firing when an animation is still active.
  _if(self.pop_animationKeys.count > 0) return;

Hope this helps someone. I would branch and commit, but am too lazy. Sorry :)

Fantastic control though. Great Work.