[Tracker] trackerbird fixes

[Michael Lipp <mnl mnl de>]

Hi,

after being annoyed about the erroneous trackerbird for quite some time,
I finally decided to dig myself into it. I couldn't find any
corresponding bugs in the bug database. I think, people have given up on
this component because it seemed to be unmaintained and thunderbird has
its own search facility (but I like the combined search). Or the bugs
never reached "upstream" (you find some in the Suse/Ubuntu/Fedora bug
trackers).

I fixed the following problems:

1) Trackerbird doesn't work at all with TB24 due to interface changes.

2) Thunderbirds sometimes "freezes" when trackerbird is enabled (you
find that in a lot of forums and bug trackers, e.g.
https://bugzilla.mozilla.org/show_bug.cgi?id=930492)

3) Improved output via dump statements and also added some reporting to
the thunderbird console in case you haven't enabled dump. This is only
done for some "hot spots", though.

If you're interested in merging the changes, you can pull them from
https://github.com/mnlipp/tracker.

What I don't like yet is that mails are found when searching as Mails
but also as "Douments" with "Loading..." being displayed. Going to look
into this as well, but I'll have to better understand the data model first.

 - Michael