* kontact plugins provide a DCOPObject to handle newInstance calls - if launching
  the standalone app (as is the case with mailto: links, but not only)
* the above isn't done if standalone app was already running when kontact starts.
  In such a case the plugin has to watch for the moment when the standalone app
  terminates, using the DCOPClient signal. Then it can create the above.
  Note that once this happens, kontact "takes over", the standalone app can't be
  launched anymore. Maybe some people might want a config option for this one day.
  The above two cases are implemented in a single templatized class, the 'watcher',
  so that the plugins need minimal change.

Two bugfixes: todoplugin.desktop lacked exec name, summary-view had a stray
setNotifications(false).

Wrote test plan in uniqueapphandler.cpp. If you change something relating to this,
you have 16 cases to re-test :)

svn path=/trunk/kdepim/; revision=276850