tigefa4u projects Trac

Follow-up to [3050] to fix authentication for tracd with a base path. Thanks to Rui Lopes for the patch. Closes #2932.

WorkFlow:

* `web_ui.TicketModule` and `api` have been ported to new API.
* Fields are now rendering themselves, as are controls.
* All fields are now provided by `ITicketFieldProviders`.
* Custom fields can be any type provided by `ITicketFieldTypeProvider`. The default field types are provided by `api.BuiltinFieldProvider`.

End tag from HTML builder should be a {{{Markup}}} instance.

Applied a patch that adds a --base-path option to tracd. This will make it easier to run tracd behind a proxy on a non-default location. Closes #2932.

WorkFlow:

* Fix custom field issues introduced last commit.

* Big trunk merge log:trunk:2983:3047

Correctly initialize `wsgi_multithread` member in standalone WSGI server. Thanks to Rui Lopes for reporting the error.

Remove empty navigation list in anydiff module (invalid HTML).

Fix typo introduced in [3044], and fix wiki formatter test that expected unescaped links for revision log links.

Enable the callback of `IWikiSyntaxProvider` to return objects other than `unicode`/`str`, so that we can return a `trac.util.markup.Element`. Converted most of the implementors to do that, too.