tigefa4u projects Trac

`IWikiSyntaxProvider` related unit-tests are now dispatched in their relevant modules.

* Better display of wiki unit-tests failure, so that it's easy
to grasp the difference between ''expected'' result and
''actual'' result.
* In `trac.wiki.tests.formatter`, the link resolver syntax is tested
using a sample link resolver
* finally, there's a test file trac/tests/allwiki.py file which
can be used to test all the wiki related tests in Trac core.

Now it becomes fairly easy for plugins to add their own tests
for the wiki syntax they provide.

Use the wiki formatter test title as the ''shortDescription'' of the test.

Spam filtering as a plugin... mostly untested and highly experimental.

Restarting spam-filter branch as plugin.

Fix stupid error in ticket module introduced in [3145].

Wiki unit-tests restructuration.

* Make it possible to add a title for wiki tests.
* Added such a descriptive title for all the existing tests,
with a comment indicating what should be done with the test
* `(MOVE)` means the test will be moved closer to the
corresponding `IWikiSyntaxProvider` (similar to what was
done in r3122)
* `(FIXME)` means the test should be changed in order to use
a generic link resolver

In TracBrowser, move the logic for building the hrefs used for changing the sort order from the template to the python code. This fixes #3033.

Experimental hooks for pre and post processing of wiki page changes (for spam filtering).

Add hooks for listening to, and potentially rejecting, ticket changes, based on patch by Alec. Closes #2176 and #3029.

Adding a regression test for #2665.