Fixes #5409: Adds visible :focus styles for nearly every link/input
Allow :focus to match buttons as well as anchors
Darker outline on rss/bookmark
Removed ?> tags from the end of the core php files
Merge pull request #5444 from Srokap/develop

Removing trailing ?>
added database queue
ported notifications code to use DIC with service class
updated documentation for notifications service factory
updated documentation for coding standards
added more documentation
made the documentation plugin developer friendly
added an example of messages providing a site delivery method and bookmarks adding a notification event
not depending on global state in notifications service
pulled hooks out as dependency
added more unit tests
reorg to accomodate a SubscriptionsService
pulled out subscription code into a separate service
pulling subscriptions from db
added mock db to notification unit tests
added unit tests for subscription class