Add Controller::redirect() override so we default to 301 instead of 302.
Change Tag and TagName routing and controllers.
- make init.php to define the tag module routes.
- change __call() to action_show() in Tag controller.
- add check that tag id exists (and throw 404 if not).
- move TagName controller to action_find_by_name() in main Tag controller.
- revise use of redirect and args for K3.
Merge pull request #306 from shadlaws/tag_routing

Tag routing