Menu Bar

[Jeremy Bicha]

In accordance with https://wiki.ubuntu.com/MenuBar I propose we refer
to the top panel as the "menu bar." The menu bar is the row stretching
across the top of the screen containing the Ubuntu button, application
menus, and status menus (specifically application status menus and
system status menus although I'm not sure users care about the
difference).

This is a big change to the docs so I want to get feedback first.
Especially as we've had trouble deciding the best names for this
stuff.

But then again, the Unity developers have multiple names for things.
Developers call the Ubuntu button the BFB or the Home button. Menu bar
sometimes only refers to the app menus (especially in earlier
references). The status menus are usually called indicators. And the
AskUbuntu "authoritative guide" is out of date.

I believe we're calling all of the menus by their right name except
for the controversial and perhaps arbitrary Session Menu (I've been
thinking System Menu is a better description for how the thing
currently works but I need to get the Design guys to agree so that I'm
not just making up my own names for things.)

Jeremy