Finish changes to recent.py for using the registry

[Siegfried Gevatter]

Finish recent.py.

[Siegfried Gevatter (rainct)]

revision <email address hidden> (1329)
Author: Siegfried-Angel Gevatter Pujals <email address hidden>
Date: Thu 2010-01-28 21:13:11 +0100
Branch: zeitgeist-trunk
Bugs: https://launchpad.net/bugs/513296 fixed

    recent.py: make full use of the data-source registry

    The GtkRecentlyUsed data-source does now connect to the DataSourceRegistered
    signal, in addition to requesting everything at startup, to have a complete
    list of actors for which there are loggers.

    The corresponding event interpretations are also considered, so that if
    CreateEvents are being inserted but VisitEvents not, the data-source will
    continue taking care of those.

    Remember that in theory the assumption "if a data-source registered an event
    template with actor X and event interpretation Y, so all Y events for app
    X are being logged by it" can't be made, but in this particular case of the
    GtkRecentlyUsed data-source we'll consider it as valid.

    Also note that the changed in this commit don't take into account whether
    the data-sources providing logging for a particular actor are currently running
    or not. This makes sense, as else we'd end up with repeated events anyway
    (when the events aren't logged at exactly the same timestamp by the data-source
    and into GtkRecentlyUsed), but given that data-sources can't be deleted from
    the registry, ignoring an actor forever is not so nice. The best solution would
    probably be adding a RemoveDataSource method to the registry.