* Add action-setmultiplefields and setmultiplevariables, and extend action-sendmessage
* Add getfield operator
* Remove getfield operator
See discussion at https://github.com/Jermolene/TiddlyWiki5/pull/6130#issuecomment-949911439
* Add docs
* Adjust whitespace
* Add support for assigning multiple indexes to action-setmultiplefields