[orca-list] Now try matrix.org with master

[Joanmarie Diggs <jdiggs igalia com>]

Hey again.

I'm afraid I'm being as spammy and floody as matrix.org. <grins> I just
committed a change to master to ignore a few, very specific,
children-changed events:

    * If the child being added is missing
    * If the child being added is defunct
    * If the child being added is an image

Having done so, matrix.org works way better for me. This should be a
safe commit. After all, missing and defunct children are events we can
do nothing useful with anyway, so why even add them to the queue? And we
do not do anything when the child being added is an image -- other than
queue it, dequeue it, poke at it to see if we care, and in the end
conclude we don't. So, again, why bother?

Having said that, as always please test. If you think there's a
regression from this commit, please capture a full debug.out so I can
take a look.

Thanks!
--joanie