Numerous style changes to the 'edit message' dialog. The save,

cancel, and address book buttons now occupy the navbar instead of
a bunch of controls that shouldn't have been there anyway.  I
also fixed a javascript bug that was making the addressbook popup
silently fail in the background if we were in a room that didn't
require message recipients.
The attachment dialog now sits above the message body pane, but
this will soon get migrated into the navbar as well (maybe another
popup).
Finally, the background of the message entry div now more or less
occupies the entire space available to it; this still needs more
tuning in order to make the editor occupy the correct amount of
space in the pane.