Event handler improvements (cont.)

Changed to sort on add from sort on process for efficiency.  Some
events (e.g. AUTH_ACL_CHECK) could be trigged many times in a single
page request.

Video/audio additions

Add ordering to event handlers

add Reply-To and Sender to apply cleanAddress

Allows a sequence integer to be supplied when registering to handle
an event.  When processing an event, handlers (hooks) will be
executed in ascending order of their sequence number.  If two or
more handlers have the same sequence number their order of
execution is undefined.

A handler wanting to be first, should use -PHP_MAX_INT.
A handler wanting to be last can use PHP_MAX_INT.
There may be conflicts if two or more plugins use these values in
the expectation that they will guarantee being first or last.

fixed pagetools being inaccessible on screens lacking necessary height, and aligned them to content when on smaller screens

Snippet fixes

previously it never returned any users

Mediamanager: rename radio name attributes for sort and list buttons to

fix fs#2851
related to http://bugs.jqueryui.com/ticket/8761

using http://cleancss.com/