Currently included jQuery is old by now, v1.6.2. We should update to
1.8.3. This allows us to take advantage of the latest form of jQuery
event delegation ($.on). I don't think it wise to update to jQuery
1.9.x yet, as many 3rd party scripts still need to be updated to cope
with its deprecated features ($.browser). Therefor, 1.8.3 is the latest
and most widely compatible stable version right now.
PHPBB3-10155
Add the jQuery JavaScript library to all pages, giving modifications
instant access and allowing for any future core JavaScript to take
advantage of it.
Also introduce a global /assets directory for assets that are shared
between styles.
PHPBB3-10155
