Make XMPP use the Bioclipse usermanager

It also:
* Removes the XMPP topmenu and preferences page
* Update the cheat sheets according to points above
* Adds help-pages to the help context
* Adds javaDoc and copyright to XwsLoginOutListener.java

I know there where talk on the bug meeting about that it was no point working on this bug. My reason for finish it is that it was that it almost done then, and I thought that not finish it would be more waste of time (i.e. the time already spent on it) than putting some more time on it and thereby get it done...