This adds the following changes when viewing a list of discussions and
forum_enabletimedposts is turned on.
* Discussions a student wouldnt see right now are dimmed (timestart in
future or timeend in the past).
* A icon appears next to the discussion subject, the tooltip for this
icon displays the display start and/or end time. This only appears for
the user that made the discussion or has permission to
viewhiddentimedposts.
These two changes achieve a couple of important things, namely, teachers
will not mistakenly think their students can see a discussion when
viewing the list if they've later forgot that they set a time limit on
it (or indeed if someone else put it on their discussion without them
realising). Additionally it makes it easy to see from the list when
different discussions are set to be released without having to go in and
edit them to find out.
Change-Id: Ia1818b33c00adae0dad72df8e170a078fb66cd76
* class html_component does not exist any more
* class html_table rendered via html_writer::table()
* html_table, html_table_row and html_table_cell have public $attributes property to set their CSS classes
* dropped rotateheaders feature, should be added again after more research of possible ways (<svg> is not nice IMHO)
* dropped possibility to define CSS classes for table heading, body and footer - can be easily done and better done using just table class and context
