#59 window numbers vs. special windows

[Oswald Buddenhagen]

don't assign #1 to the project window. instead, allow
assigning arbitrary fixed keys to all types of special
windows (including message window, project window,
clipboard, etc.), and allow specifying a list of window
numbers that are never assigned.
that way you could configure your current scheme
without problems, and new users without legacy could
use something reasonable. ;)