model: add outdated property to changeset comment to check if comment is outdated

js: add failure callbacks to ajax functions to allow custom behaviour on failed requests

changeset: add new diffs to changeset controller

ux: make the diffset header more pronounced and show commit details if a commit is available, also color it orange when a diff has been limited

diffs: move diffmode to template global context and add it to session so mode is saved between requests

diffs: rename .diff to .filediff and use .diffset for grouping a list of diffs since .filediff refers to a single file rather than the entire diff

diffs: add commit id argument and use id of filediff for identifying collapse blocks and links, this allows render_diffset to be used multiple times on a page without conflicting with each other

diffs: add ruler to diff output to show eg. 80 char line

nix: Add `sourcesOverrides` argument to shell.nix to set the vcs server path in jenkins.

nix: Use vcsserver from config instead of using command line argument.