JSON hierarchy caches.
JSON before XML and non-js JSON sourcing.
Stronger globals.
Removed JSTree formatting from json cache files.

Still needs to be cleaned up and generalized and documented.
Fix inconsistent sort behavior.
Fixed sorting inconsistency.
Merge branch 'release-2.3'
Added language copystring utility.
Added strings for alphabrowse improvements.
Merge branch 'release-2.3'
display headings in table on alphabrowse home (bootstrap only)
Small German correction

* note_780_5 is "absorbed"
* German value translates to "absorbed into", so the other way round
* proper translation is "Darin aufgegangen" ("Absorbiert" would sound very chemical)
* see for MARC: http://www.loc.gov/marc/bibliographic/bd780.html
* German translation by Deutsche Nationalbibliothek is identical: http://d-nb.info/996983511/34
Merge branch 'release-2.3'
Avoid direct call to getConfig().
Adding test for language file consistency.
- Resolves VUFIND-760.
Style fix.
Added mechanism to proxy image URLs; used this to display Summon thumbnails.
More conservative Summon thumbnail behavior.
Eliminated potentially confusing static variable.
- Expanded tests.
More appropriate parameter order in assertion.