[Tracker] Master open for 1.11.x. Request for reviews

[Carlos Garnacho <carlosg gnome org>]

Hey all,

Just the mandatory heads up that master is open again for development.
I'll use the opportunity to request review on 2 new features:

- Add libtracker-notify to wrap GraphUpdated.
  https://bugzilla.gnome.org/show_bug.cgi?id=773028
- Add client-side support for HTTP sparql endpoints
  https://bugzilla.gnome.org/show_bug.cgi?id=773031

The latter is quite accessory ATM, I did it as a playground to
Wikidata query service, which doesn't seem ready for prime time yet,
but the patches make it functional through tracker, which is cool.

I consider the former feature more important though, this is something
we've usually deferred to clients, but that plus bad documentation [1]
has lead to implementations not getting all details right (it's hard
to start with... see for example [2]). This IMO brings bad perception
on Tracker even if it's not necessarily at fault.

My hope is that all the scattered GraphUpdated callback
implementations will switch to using TrackerNotifier over time, so
bugs are fixed in a centralized place and tracker-side performance
issues can be discarded/fixed with sysprof/perf/etc.

Cheers,
  Carlos

[1] If we can consider
https://wiki.gnome.org/Projects/Tracker/Documentation/SignalsOnChanges
, and examples/libtracker-sparql/class-signal.c as such.
[2] https://bugzilla.gnome.org/show_bug.cgi?id=764419#c3 or
https://bugzilla.gnome.org/show_bug.cgi?id=757326#c3