Custom Popover animator

[LawrenceHan]

Hi @wtmoose ,

I think this project is brilliant, and I want to add a popover animation for it, but since I lack of auto-layout and related knowledge, I'm asking for some advice or even refinement.

The animation is under popover branch, you can run the demo project to test it.

[LawrenceGlow]

Hi @wtmoose, It is a cool animator in my opinion, all I'm asking is to have a look yourself. If it is not a good PR please tell me, so I can improve it.