B07002 - hiding under nothing?

Clear the uundetected status during level changes in case
the character was hiding under something immediately prior to the
change.  Don't set hidden status at the destination even when
there's something to hide under--it'll take a turn to hide again.

src/do.c

@@ -1,4 +1,4 @@
-/*	SCCS Id: @(#)do.c	3.4	2002/05/31	*/
+/*	SCCS Id: @(#)do.c	3.4	2002/08/11	*/
 /* Copyright (c) Stichting Mathematisch Centrum, Amsterdam, 1985. */
 /* NetHack may be freely redistributed.  See license for details. */
 
@@ -987,6 +987,7 @@ boolean at_stairs, falling, portal;
 	fill_pit(u.ux, u.uy);
 	u.ustuck = 0;				/* idem */
 	u.uinwater = 0;
+	u.uundetected = 0;	/* not hidden, even if means are available */
 	keepdogs(FALSE);
 	if (u.uswallow)				/* idem */
 		u.uswldtim = u.uswallow = 0;