Closes #97

See https://mail.xfce.org/pipermail/xfce4-dev/2022-May/032915.html

- exo-csource is deprecated and moved to xdt-csource
- Bump minimal xdt version

Because the service is out since a couple of months.
Instead of supporting every image hosting service out there,
at some point I hope to introduce user custom actions.
Instead of binary plugins, a simpler approach similar
to Thunar Archive Plugin .tap text files should be enough
and user-friendlier.

Signed-off-by: Jackie Huang <jackie.huang@windriver.com>

- move common callbacks to screenshooter-job-callbacks.c
- only pass screenshot name and title to screenshooter_upload_to_imgur
- set a jobtype property on the job gobject to figure out if we need to show imgur or zimagez urls
- add a create_throbber_dialog function to build the dialog displayed during upload

Finally, screenshooter-imgur.c and screenshooter-zimagez.c only have the upload-related code.

Eric Koegel authored 10 years ago and Landry Breuil committed 10 years ago

Based on the xfpm appdata, the spec is available at:
http://www.freedesktop.org/software/appstream/docs/sect-Metadata-Application.html

Technically, this doesnt add a dependency since libxml is already a dependency of libsoup..

link screenshooter-imgur.c and .h to the build.
add {CURL|JSON_GLIB|SEXY}_{CFLAGS_LIBS} where appropriate

All this should be made conditional of course....

To allow building in directories other than the top srcdir.

- Don't use a versioned library.
- Build as a module.
- Only export needed symbols.

This makes the "Help" button functionnal after the changes to xfhelp4.

This allows us to remove our local copy.