[PATCH 0 of 1] diff: add collapse to simple diff and make it configurable

[Jan Heylen]

Hi,

this is a patchset that makes simple diffs collapsable and it's default
behaviours configurable. The first patch are the generic code changes.
The second patch is how we use it, hardcoded in pull requests. I don't this
is to be pulled in, maybe if this would be a configuration option. By default,
without the second patch, the pull request diff only becomes 'collapsable'.

br,

Jan