[IMPORTANT] :user-level property removed

[Christopher Roy Bratusek <zanghar freenet de>]

Hi all,

some weeks ago I removed the :user-level property from defcustoms it
has been deprecated years ago, so no-one should be using it anymore.

But there still might be some old script making use of it, so refer to
this bit of doc now in README.IMPORTANT:

:user-level property
********************

Defcustoms have a set of propertys, one of them :user-level
is deprecated for years now, with 1.6.0 it's fully removed.

grep your scripts for :user-level and remove it, except that
your scripts options will show up in SawfishConfig again,
it has no sideeffects.

Chris