Generating the templatesUsed list is relative slow, and is only
used in an obscure part of the editor, so only generate it when
needed.
Bug: T209078
Change-Id: I1cecdad65b80c4c9b1746e752ea4b41bc0fc0037
Added 5 methods for MetaDialog (documented in code comments)
extractSettings
compareSettings
getAllWidgets
assignEvents
updateActions
Added 2 fields to MetaDialog
oldSettings
widgetList
Apply changes button now is only enabled when there are new changes
Added getFieldsets method to all subpages
Bug: T207719
Change-Id: Id51acf6c754d9a2572811775d83983e6ab9395b7
Also, pass $overlay to all PageLayout subclasses used in ve.ui.MWMetaDialog
and ve.ui.MWTemplateDialog/ve.ui.MWTransclusionDialog, for consistency.
Bug: T191395
Change-Id: Ib7ed2e2c04ff7930be1161bd2b981180ee59557a