conf -> registry

[Anil Madhavapeddy]

A known problem since this change is that the "notconfigured" stuff in
the index.php of applications doesnt work.

The only dependency (and hence why the app has to guess where horde is),
is the horde/css.php file.

At the expense of making the not-configured error message look uglier
(and we can fix this by hardcoding a "default" fallback css), I'd like
to remove the dependency for the error-messages on Horde.  It'll
simplify the index.php stuff quite a lot, and not make any assumptions.
In other words, if someone just downloads IMP without Horde, it'll
display a sensible error message without external dependencies.

There are probably other small problems lurking around - if everyone
could update their applications and hunt around now, it would be good.

Anil