i.e. Overview is now a mostly pure aggregator again.

The new commit / blip feature is now maintained in `blip.kummerlaender.eu`.

This works out nicely -- the only thing still missing is an archive and maybe filtering support.

This is the starting point for extending _Overview_ to support various
types of recent updates (i.e. not just blog articles and commits over a
certain message size).

While direct fetching and rendering of markdown-formatted Git commit
messages is an attractive concept, this new approach should be much more
flexible. As a side benefit commit entries can now be edited and
expanded compared to their fixed Git reference. e.g. retroactively
expanding upon older commits or adding example media that doesn't
strictly belong inside the actual commit message.

Fetching external resources during the actual build became problematic
after the last major Nix update (build purity was improved).

The sensible way of doing things in Nix seems to be to declare ALL
build dependencies prior to the actual build -- this includes
e.g. ATOM feeds to be aggregated.

I am probably not going to do the same for the individual repository
feeds as this feature is going to be replaced with a more general
_microblog_-like subpage.

See 76f8676 @ blog.kummerlaender.eu

Only seems to be a problem on some browsers such as Edge. Nevertheless
this patch fixes it for all of them.

The _more_ link symbol is displayed with an ugly blue background in recent versions of Microsoft Edge (see MS issue 11635143).

analogously to blog.kummerlaender.eu

* navigation now aligns itself properly on smaller screens
* increased line height for both the article teasers and commit message list items

* removed _justify_ text alignment for list items

* a commit must now have at least three list nodes to be selected for inclusion into the list of latest commits

* fixed menu list padding to prevent premature line wrap

* _dotfile_ changes don't really deserve _first-class-representation_ on a overview page

* the commits were only sorted by date and not by time

* commit `71a637` in upstream _InputXSLT_ activated namespace comprehension for `InputXSLT:read-file` and `InputXSLT:external-command`
** this caused both the article and the repository feed queries to fail as they are inside the ATOM namespace

* `id` has to contain a valid URL
** i.e. it now contains the same value as `link/@href`
* `author` was missing