PR mode: show other potentially fixed issues by content and linked issues.

[OrbisK]

Feature Request

unsight should show all issues that are not already linked for PRs.

For Ex 1: by looking at all the related issues of #123 (linked via the description).

For Ex 2: by the context of the description and possibly the code.

This should enable us to potentially resolve other related issues that have been addressed incidentally.

Ex 1:

PR:

fixes #123

This PR does stuff that should fix foo and bar

Issues:

unsight does already link #123 and #321

#123

foo not working

#321

foo and bar not working

Ex 2:

PR:

fixes #123

This PR does stuff that should fix foo and bar

Issues:

unsight does NOT link #123 and #321

#123

foo not working

#321

bar not working