[sugar] Journal Object Picker in Read

[Morgan Collett]

I filed #8350 regarding adding the journal object picker to Read, for
the case when it is launched from Home View without a document.

There was a recent discussion on the library list about this, since
the show_launcher setting isn't relevant any more - Read appears in
Home View if you star it. (If Read is installed in the software
updater, it will be starred...)

I have implemented this, and could release it for 8.2.1, but the
journal object picker doesn't currently have any filters for an
Activity to restrict the view to only relevant entries - so it pops up
with the entire journal visible - images, Write entries, Browse
entries, etc where all we can handle in Read are relevant downloaded
documents, and previous Read instances.

Is this going to cause more problems than it's worth?

I could make the object picker pop up again if the selected entry
failed to load, if that helps.

An alternative to using the object picker is to have a string break
and add a dialog that explains that you launched Read without a
document, and so it isn't useful, and make that stop Read when
acknowledged.

Regards
Morgan