New filtering changes landed

[Joe Shaw <joeshaw novell com>]

Hi,

I just landed code which adds some flexibility to the filtering system.
Expect delays.

Filters can now themselves create Indexables which the daemon will in
turn filter and index (and so on).  This will allow us, when someone
actually writes it, to index the contents of archives like zip and
tarballs.

In a similar vein, the mail backend can now create child Indexables and
as a result now filters and indexes all of your mail attachments.  In a
pretty neat demo I successfully searched for my cousin's name and got a
hit of the wedding invitation in MS Word format that my father sent me
as an attachment in 1999.  The Best tile still needs a fair amount of
work to nicely handle these things, but it's a start.

Because of these changes, things might be a little unstable for a few
days.  I had to bump up the minor index version on the mail backend,
which means that Beagle has to reindex all of your mail.  It also means
an updated GMime requirement.  We now require 2.1.15.  As always, you
can download gmime source from here:

        http://spruce.sourceforge.net/gmime/sources/v2.1/
        
Joe