renaming global queue controls

i find many people not using the global queue correctly. maybe renaming some of the controls in the global queue window (toggled by ctrl-q) would help. what about renaming
- the window title from "Transfers" to "(Global) Queue" (as well as the "View" -> "Toolbars" menu entry)
- the "Global Queue" tab to "Transfers"
- the "Queue Source" tab to "Sources"
this would hopefully make things clearer.

btw: when is the obsolete session queue finally to be removed? the existence of both a session and global queue just confuses people even more.