Fix pagination [#46302531]

JS index-controller bug "> 1" instead of ">= 1" would not create
10-block of pages if number of pages was less than 20
Fix height of permissions-modal body

did not take scrolling of page into account
[Fix #49123259]
Fix display icon for empty extension

[Fix #47259943]
Fix Splashscreen; splashscreenset can be filter set

make MediaSet and FilterSet derive from common ancestor
MediaResourceCollection so it is clear that each should implement
included_resources_accessible_by_user
Added feature test for explore page
Removed after all hook from meta_contexts_controller_spec
Monkey patch db-structure dump to include data

also include db/structure.sql
JS translation for media_resource_arcs.
JS translations for media_resources.
Merge branch 'rca_translations' of github.com:zhdk/madek into rca_translations