Collapsing and Expanding a Group using CircularLayout does not remain at same location

[walter]

GoJS version 1.7.19

Added the Vue.js sample, demonstrating a simple GoJS app in the Vue.js framework. Fixed a bug in DraggingTool.moveParts where it was incorrectly shifting Nodes when Nodes shifted by differing amounts. Extended RotatingTool to work on link labels; the user still cannot rotate whole Links or the Link.path. Restored behavior from 1.6 of Model.fromJson such that linkdata.points property value is of type List. Version 1.7 had allowed that property to remain as an Array of numbers. When a Group.lay…