Fairly certain this adds the feature in which the user may click the online notification to open a chat with the user coming online.
Translators may want to look at the xml changes of this change to see what to update
Removes old LegacyMultiAttachmentSupport patch
Moves LLAvatarName-centric functions into LLAvatarName from elsewhere.
Adds boost::signals2::connections to name polling places.
Removes more old icky static callbacks
Merge from Alchemy, credit where due~
Update notifications.xml to have a bunch of the tags from upstream to ease diffing
