References dialog cleanup

Objectives:

* Remove the whole toolbar subset thing, it's up to the creator of the
  subsurface to know what is and is now allowed, and the commands were
  still passing through unfiltered
* Correctly separate initialization from opening - fix issue where opening
  the reference dialog multiple times will keep adding more and more
  controls

Changes:

ve.init.Target.js
* Remove getToolbarSubset method

ve.ui.MWReferenceDialog.js
* Add toolbar tools and surface commands configs to reference dialog,
  including the things that are safe to use in references
* Move creation of field sets and reused controls to initialize method
  to prevent re-creation each time the dialog is opened
* Move static initialization stuff to the top near the other static stuff

Change-Id: I1c8577d17c506bac76e61b2b036655c59ef5a218
Merge "References dialog cleanup"