Make page title link link to recent page by default.

Linking to All Posts isn't very useful, since most of time user care
about latest posts rather than all posts. If he want to see the whole
thread, he can still use the "All Posts" button on the bottom anyway.
Change redirect path after reply to last 5 posts.

To reduce load time in large topic. Since user can reply, it is also safe
to assume that user don't need to re-read the whole topic again.
Fix stylings for error page when post wasn't successful.

The individual error page when user make a reply to a locked topic was
left unstyled when we convered from Bootstrap to non-Bootstrap.