Treeportlet: Implement deferred tree rendering.

When having a large repository-tree with more than 2000 objects,
the three portlet slows down every site reload. To avoid this performance issue
we render the the tree deferred.
Merge pull request #250 from 4teamwork/pg_deferred_treeportlet

Treeportlet: Implement deferred tree rendering.
Rework Templatedossier listing tests.
Limit query depth in templatedossier listings(documents, trash).

In some GEVER installations it will be allowed to nest the templatedossiers.
Rework complete templatedossier functionality:

* Move the files in to a subdirectory
* Split them up in to separate files
* Rework the tests (using ftw.testbrowser)
* Pep8
* Pyflakes
Templatedossier: cleanup the types.xml.

* Drop no longer existing Mail behavior.
* Fixed copy&paste fail.
Allow nested Templatedossiers.

This change should not be a probleme for existing installations, because
adding templatedossiers is protected by a separate permission, which only
the `Manager` Role owns.
Setup: Activate navigation portlet on the templatedossier.

The templatedossier could now be nested, so it makes sense to
replace the `repository-treeportlet` with a locall navigationportlet.