Issue #240: Format issue tracker links (and others) in changeset and pull request comments (conservancy/kallithea)

[Samuel Delisle]

New issue 240: Format issue tracker links (and others) in changeset and pull request comments
https://bitbucket.org/conservancy/kallithea/issues/240/format-issue-tracker-links-and-others-in

Samuel Delisle:

Issue tracking links (`issue_pat`/`issue_server_link` ...) are currently only formatted in commit messages.

It would be nice if it was also possible to use them in changeset comments and pull request comments.

In addition, it would be nice to have a built-in way to create internal links while commenting. For example:

* `pr:123` could link to pull request #123 (this one cannot be configured manually with a custom `issue_pat_...` entry because pull request links don't seem to work globally, they need to be prefixed with the repo url)
* `repo:<repo>` could link to a particular repo (or repo group) and display its full name instead of its id
* `changeset:<changeset>` or `changeset:<repo>:<changeset>` could link to a particular changeset. If <repo> is not specified, the changeset would be assumed to be in the current repository. Maybe changeset hashes could even be automatically recognized without requiring a prefix?
* `file:<filename>` or `file:<repo>:<filename>` or `file:<changeset>:<filename>` could link to a file

If comments have a global id, maybe we could even link to another comment.

This would make it possible to refer to other elements in a more concise way without giving a full url, which would become invalid if the server home url changes for some reason.