[ci skip]

This will allow for the removal of a lot of duplication from the
reference filters.

For simplicity's sake, since we're testing the actual referencing, we
just force the permission check to always be allowed.

Commit ranges, commits, external issues, issues, labels, merge requests,
snippets, users.

Bootlint integration

Clean up code around commit mentions.

Builds upon !527.

See merge request !528

Revert disallowing usernames to end in period.

cc @JobV @jacobvosmaer

See merge request !545

improve new project options

* Simplify new repo commands
* Include directions for how to add an existing folder that is either
already a repo or not yet a repo

Replaces #7918.

Remove access control for uploaded images to fix broken images in emails

Replaces !530.

> This MR removes the access control for uploaded images. This is needed to display the images in emails again.
>
> The previous solution to base64 encode the images had to be reverted, because not all email clients supported it.
>
> If possible this should go into the 7.10 release.

See merge request !533