Added possibility to display tickets with thousands of articles, thanks to Moritz Lenz @ noris networks.
GUI improvements pending.
Squashed commit of the following:

commit 7beb415abeedbb17976b7c7193d3f4f9141daee4
Author: Moritz Lenz <mlenz@noris.net>
Date:   Fri Feb 21 11:08:24 2014 +0100

    Tests for ArticleContentIndex

    in particular for the new Limit and Page options

commit ac71fe14bb22ab72a45f19b2a5b8d0a571b79ec4
Author: Moritz Lenz <mlenz@noris.net>
Date:   Fri Feb 21 10:45:45 2014 +0100

    remove obsolete TODO comment

commit 2b1b5e64d882c5577df03da6cfd3e7e43c1b0b53
Author: Moritz Lenz <mlenz@noris.net>
Date:   Tue Feb 18 17:52:54 2014 +0100

    use heading

commit 48dad2c1a821fe220f3d624931d8003c766ede42
Author: Moritz Lenz <mlenz@noris.net>
Date:   Tue Feb 18 15:40:23 2014 +0100

    Unit test for ArticleCount

commit 29b1e5b167a0ee2d38fdcef08b91bf9edb226c34
Author: Moritz Lenz <mlenz@noris.net>
Date:   Tue Feb 18 14:59:51 2014 +0100

    Cleaner HTML, even it does not look as pretty

commit ebfbf1fe4cf0d00e308f29ade1f3ebe5d58f3b9a
Author: Moritz Lenz <mlenz@noris.net>
Date:   Tue Feb 18 14:21:02 2014 +0100

    Make article limit for ZoomExpand configurable

commit c551b6689e9354275693d86435492f1800b9f6a6
Author: Moritz Lenz <mlenz@noris.net>
Date:   Tue Feb 18 14:16:01 2014 +0100

    Bump limit to 1000

commit 0c2260a039c4825b8ff52681d27e14292d321cc6
Author: Moritz Lenz <mlenz@noris.net>
Date:   Tue Feb 18 14:15:47 2014 +0100

    Add page number to ZoomExpand links

commit f218741d7baddf08e4704e7026fd3ab71ad055ce
Author: Moritz Lenz <mlenz@noris.net>
Date:   Tue Feb 18 13:40:21 2014 +0100

    First shot at actual pagination in AgentTicketZoom

commit 6b8a3594eb2271092cc5f007c9584be74115a02a
Author: Moritz Lenz <mlenz@noris.net>
Date:   Tue Feb 18 11:17:44 2014 +0100

    Limit list of articles on AgentTicketZoom

    TODO: show pagination

commit 42644fd2a3e70cd4905018be036a3ef47239562e
Author: Moritz Lenz <mlenz@noris.net>
Date:   Tue Feb 18 09:05:08 2014 +0100

    Infrastructure for paged article boxes

    Implements Limit and Page parameters for ArticleGet and ArticleContentIndex.