[orca-list] notification messages

[jose vilmar estacio de souza <vilmar informal com br>]

Hi all.
I created a script in orca so that orca can repeat the notification 
messages. It must applied to latest orca from git repository.
How it works:
User press orca_key+n, and orca repeats the last message.
User press orca_key+n two times and orca repeats the message above the last.
User press orca_key+n three times and orca presents a list of messages 
in which user can navigate using home, end, up and down. To exit from 
the list user may press the escape key.

Please test and send me corrections, suggestions, complaints, beer, 
pizza and so on.
Visit https://bugzilla.gnome.org/show_bug.cgi?id=627451 for more 
information and to get the patch.
Thanks.