20121230
========

URL algebra
-----------

The ADMIN_URL variable in linolib.js didn't 
correctly handle the case of an empty :attr:`lino.Lino.admin_prefix`.

This was because I had once again tried 
to reproduce Django's rule for `MEDIA_URL
<https://docs.djangoproject.com/en/5.0/ref/settings/#media-url>`__ 
which must **end** with a slash if set to a non-empty value.

After fiddling with different constellations I now gave up.
I just cannot figure out why the hell they have *such* a rule.
IMHO the rule should be easy because that's a 
common configuration option, but not at the price of performance.
Added a note about the fidderence in the docstring of
:attr:`lino.Lino.admin_prefix`.