Allow disabling of line wrapping in diff

Description

Line wrapping was previously an option when viewing diffs, however it was removed in https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/396. I understand why it is the default, but I don't understand why the button was removed entirely.

Proposal

Re-instate the line wrapping toggle

Links / references

Documentation blurb

Overview

What is it?

  • A button to toggle line wrapping in a diff

Why should someone use this feature?

  • When they don't want lines to wrap

What is the underlying (business) problem?

  • Makes it hard to scan the beginning of lines in files that have particularly long lines, e.g. log files, or developers who for whatever reason like really long lines

How do you use this feature?

  • Viewing merge requests that have particularly long lines, and the wrapping ruins the intended appearance of the code.

Use cases

  • Looking at merge requests diffs and don't want lines to wrap.

Feature checklist

Make sure these are completed before closing the issue, with a link to the relevant commit.