This commit adds the list of changed files in the revision
view but also the diffs (unified and side-by-side) of each
changed file.

Those new features are reachable from the "Changes" tab
in the revision view. Computation of file diffs will
be requested once the user switch to that tab.

Regarding the diffs, they are only computed for textual
contents and diffs larger than 20 kB will not be computed
by default (the user can still manually request it
if needed).

Related: D295

Closes T972

Closes T971

  - persist cooking tasks list across browser sessions
  - enable to remove entirely or partially tasks from that list
  - ensure tasks list synchronization on browser tab focus
  - hide modals when replies of vault requests are received
  - fix progress bar color when a task failed

Closes T963

Closes: T949

Related: T949

Closes: T952

Related: T952

Closes T951

Integration of new UI components in order to cook and retrieve
bundles from the SWH vault:

  - add buttons to request the cooking of directory/revision
    bundles in relevant browse views: directory, revision

  - use modals to get user confirmation and provide optional
    email for download ready notification

  - add a new tab 'Vault' in the main browse interface to
    report the status of cooking tasks and offer download
    links once they are available

Closes T889

Related T565

Due to popular demand, this commit adds the browsing of files
in the revision view. Nevertheless, this browsing is limited
to the revision scope (no branches/releases switch allowed).

Some slight design improvements, notably:

  - swap revision id and author columns in revisions history view
  - add an icon for revision object
  - revamp revision and release views: only display important data
    (message log, author, date, parent) in the main views content
    and show metadata on demand as in the content/directory views

Closes T938

Closes T926

See https://github.com/wcoder/highlightjs-line-numbers.js/pull/22
for more details.