commit -- auto-save profile by default

[Paul Rohr]

AutoSavePrefs now set by default, so that missing profile can be created 
from builtin defaults on shutdown.  May fix #587.

  M src/af/xap/xp/xap_Prefs.h

Jeff, I noticed your comments in the code about keeping this default off, 
but I don't understand the rationale.  (Call me brainwashed, but I think 
autosaving prefs is *exactly* what the Church Secretary wants.  Ditto for 
the MRU menu, etc.)  

Feel free to come up with a better fix.  :-)

Paul