This is to let us redact them later in another filter.

Encapsulates the logic for `Gitlab::Access::WHATEVER` levels.

These fixes were performed automatically by Rubocop's `-a` flag.

And make it more generalized for all filter specs.

When this option is `:description`, we use a more restrictive whitelist.
This is used for Project and Group description fields.

Forces a `rel="nofollow"` attribute on all external links.

We only want them shortened by the filter, which calls to_s

Fixes #1690

Instead of using a fork, we subclass the filter and only apply the
`task-list` class to list items that actually are task lists.

Closes #1645

See https://github.com/github/task_list/pull/60

This just extends the HTML::Pipeline::SanitizationFilter with our custom
whitelist.

Removes header and table of contents processing from Redcarpet renderer.

Also matches CommitReferenceFilter's new behavior of always using short
SHAs in the link text.

Now when a user pastes a full SHA like
`d7f61aff`, its link text will only show
`d7f61aff` for brevity.

Prior it would return the project from the current context, which wasn't
the intended behavior.