Prior to cleaning up search params, hack in method of providing arbitrary extra query params to Solr
Refactoring of actions which dispatch searches.

Previously action composition was been (ab)used in a way that hurt
readability. Although the number of different search-related objects
is still confusing, the way searches were dispatched is now easier on
the eye and brain.
More cleanup/refactoring of the controller search trait
Misc cleanups and consistency fixes.
 - make the API controller take an entity type instead of a string
 - remove unnecessary i18n lookups on confirmations
 - add indexibility to vocabs and auth sets
More refactoring of portal views - move mainContent wrapper into core to share more widely
Fix interaction between the header and Ajax-loaded bodies
Merge branch 'master' into play-2.3

Conflicts:
	modules/admin/app/controllers/admin/Metrics.scala
	modules/core/app/controllers/core/ApiController.scala
	modules/core/app/controllers/generic/Search.scala
	modules/portal/app/controllers/portal/Portal.scala