Browser plugin, activex control, scanner bits.  Online update.

== Application online update checking ==

When we start LO, first InitUpdateCheckJobThread is created, via
UpdateCheckJob::execute() (from extensions/source/update/check/updatecheckjob.cxx),
as a reaction to a "onFirstVisibleTask" event. It waits 25 seconds (so that it
does not interfere with the startup itself), and then calls
UpdateCheck::initialize() (from extensions/source/update/check/updatecheck.cxx).

This creates one more thread, UpdateCheckThread, that regularly checks whether
we have reached the time when we should ask for the update.  If yes, asks for
that, and shows the download button in the menu (if the new update is
available).