Fixed clicking on tags
Added post deleting
Optimized API operations

Every operation updated user last login time, which was inefficient.
Changed it to update only after logins from credentials or cookies.
Fixed login remembering
Refactored entity filtering
Changed PHPunit settings to be more verbose
Added post featuring
Fixed registering multiple users with empty e-mail
Moved upgrade.php to scripts/
Added post globals
Refactored file dropper
Added basic post editing
Fixed exit confirmation
Added last edit time to basic post information