main() reorganization (trunk only)

Move some internals-related code out of port-specific main so that
it isn't duplicated a bunch of times.  One minor side-effect of this
change is that if you auto-pickup something at the very start of a game,
it will happen after any full moon/new moon/Friday 13th message rather
than before.  There's a second change for some:  the shared main() used
by several of the micro ports had a small difference in game play--if you
saved a game while on an engraving, it would automatically be read when
you resume--that will now occur for everybody [Elbereth weenies rejoice!].
pcmain() was also calling update_inventory() at start of play.  That's
unnecessary for new games, where inventory initialization triggers a call
to it for each item added to your pack; but I wasn't sure about restored
games, so everybody gets it there now.

     The Mac and BeOS ports evidently haven't been touched it some time;
they still referenced flags.move which got replaced by context.move quite
a while back.  The Windows GUI code has a declaration for mswin_moveloop()
which appears to be non-existant, but I left it alone.  I assume that the
Qt interface uses the existing main() routines; at least I couldn't find
any start of game code specific to it.  vmsmain's revised main() is the
only one which has been tested.

include/extern.h

@@ -20,7 +20,7 @@ E char *FDECL(fmt_ptr, (const genericptr,char *));
 
 /* ### allmain.c ### */
 
-E void NDECL(moveloop);
+E void FDECL(moveloop, (BOOLEAN_P));
 E void NDECL(stop_occupation);
 E void NDECL(display_gamewindows);
 E void NDECL(newgame);