Added Button to Skin2D to generate a mesh asset from the generated mesh.   Added a Sprite CutOut Shader for use in Perspective camera mode and Z sorting, use the Perspective2DSortMode on a camera to use this shader properly with sprites.  Exposed the shaders to use in Skeleton so a user can define which ones they wish to use.  When clicking on Use Shadows button in Skeleton component, if the Cutout shader is selected, it will automatically change the sorting order int to 0 and use a z value based on the sorting order value.  If clicked again it will revert to the sorting order.  Added a menu item to automatically reset the sorting order to 0 of a selected game object and it's children.