Add xxf:forall and xxf:exists
Fix #1129 "Incorrect caching of 404 and error pages"
Remove obsolete oxf.http.force-last-modified property
Fix #1131 "fr:alert-dialog: Callbacks don't support static ids anymore"
Fix #1132 "xf:model/xf:var/@model doesn't scope other model's variables"
FR: Fix language handling for pages without app/form

- in particular, this allows the home page to show the language selector
- new oxf.fr.available-languages property (without wildcards)
Implement #1054 "FR: Unpublish/republish"

- checkboxes and Unpublish/Publish buttons
- confirmation dialog
- display Available/Unavailable for each form
- unpublish/publish logic
- detail and summary pages return 404 if form is unavailable
- internationalize home page
Small refactoring
Allow Form Runner buttons to have a binding