extended ajax tabs handling: use default search tab if no active-tab cookie set yet
Merge remote-tracking branch 'origin/development' into development

Conflicts:
	module/Swissbib/src/Swissbib/Controller/SearchController.php
Merge remote-tracking branch 'origin/development' into development
* made start of request traceable - ajax spinner is added via js with request
* moved registration of loaded tabs from js into hidden field inside the tab content
* removed contentLoaded-logging (not needed anymore with load-registration inside content)
* tabs init is now only run when they're present (after search)
* fixed tab-contentLoaded check: condition now checks tab's ajax url
* cleanup: prevent reload of active tab on click
* fixed: initial rendering of tabs renders content of active one (was: first one)
* fixed: init of content-loaded flag according tab config  (did fail for secondary tabs)