[Koha] Systempreferences table

[Tonnesen Steve]

I've added support for systempreferences via the systemprefs() subroutine
in Search.pm and a systempreferences table in the database.

The systempreferences table:

create table systempreferences (variable char(50), value char(200));

So far, the only pref I'm using is for choosing an acquisition module:

variable='acquisitions', value='normal' or 'simple'

If the systempreferences table doesn't exist, you'll get errors in the
apache logs, but acquisitions will still default to normal.  Also, I
haven't added my simple acquisitions module to cvs yet.

Steve.