* Changed importVariable to store its ownvariables
Before, importVariables was creating a setWidget for every single variable it would find in its tiddlers, and it would create a long-ass call tree. Now, instead, it just accumulates the variables in itself.
* Can't use Object.assign
Learned the hardway while working on tw5-relink that Object.assign
doesn't exist in IE11. Using $tw.utils.extend instead.
* Retaining setWidget transclusion flexibility
* One more test to verify mixing sets and macros
aa817f66d2