v1.02: Updated to Godot 3.1 beta, fixed deleting Tracks

Excuse all the updates!  Been finding lots of bugs the past few days, I'm sure I'm close to hitting a pretty stable release.  

Version 1.02 ports the code over to Godot 3.1 beta, with it comes a significant performance increase.  I was afraid that porting would severely break my code, but the move was pretty easy and helped me catch a lot of bugs I had missed with Godot 3.06. 

I've also fixed tracks not deleting in the Animator, when you delete a node in the node tree, all animations with tracks referencing that node will be deleted.