added unit tests for subscription class
some cleanup of new notifications code
added subscribe functions and started deprecating old notifications code
made notifications backward compatible
fixed coding standard issues in documentation
changed name of the queue interface
made test methods a little more descriptive
added blog integration for new notifications
fixed unit tests due to new argument for database class
implemented content plugin notifications
added backward compatibility for notify_user() - will use new notification send hooks now
adds email notification sender for new notification code
passing event to notification sender
Merge pull request #5450 from cash/notifications5

async notifications
Merge pull request #5412 from mrclay/5409

Fixes #5409: Adds visible :focus styles for nearly every link/input
Fixes #5454 standardizes service names
Fixes #5423 starting real session before logging user in on install
Refs #4801 not passing size for file inputs
Refs #4801 using abbr instead of deprecated acronym for time
Fixes #4043 added parameter to elgg_get_entities_from_relationship()