tigefa4u projects Trac

* Links to files and changesets in aliases point to the base repository.
* URLs leading to resources in aliases redirect to the base repository.
* Show only real repositories in the timeline, not aliases.

From a programmer's point of view, this means that the name of a repository is always `repos.reponame`, and the `Resource` objects associated with the repository and related classes always represent real (non-aliased) resources, and can be used both for the rendering context and for permission checks.

Closes #7116.