simplify touchstone object choosing

- remove special case code from getobj for touchstone
- remove other hacks from getobj that resulted from earlier hack, solves
  the "rub on the gold stone" problem completely
- pass correct letter list to getobj from use_stone, like other callers

src/apply.c

@@ -1808,14 +1808,15 @@ use_stone(otmp)
 struct obj *otmp;
 {
 	struct obj *obj;
-	char allowall[2];
+	char allowall[3];
 	const char *color = 0;
 	static const char *ambiguous = "You make scratch marks on the stone.";
 	const char *scritch = "\"scritch, scritch\"";
 	unsigned material;
 
-	allowall[0] = ALL_CLASSES;
-	allowall[1] = '\0';
+	allowall[0] = GOLD_CLASS;
+	allowall[1] = ALL_CLASSES;
+	allowall[2] = '\0';
 	if (!(obj = getobj(allowall, "rub on the stone")))
 	    return;
 

src/invent.c

@@ -733,7 +733,6 @@ register const char *let,*word;
 	boolean usegold = FALSE;	/* can't use gold because its illegal */
 	boolean allowall = FALSE;
 	boolean allownone = FALSE;
-	boolean touchstone = FALSE;
 	xchar foox = 0;
 	long cnt;
 	boolean prezero = FALSE;
@@ -746,15 +745,6 @@ register const char *let,*word;
 #else
 	if(*let == GOLD_CLASS) let++, usegold = TRUE;
 #endif
-	/* Ugly check for touchstone */
-	if (!strncmp(word, "rub on", 6)) {
-	    touchstone = TRUE;		/* avoid silly "stone gold" */
-#ifndef GOLDOBJ
-	    if(u.ugold) allowgold = usegold = TRUE;
-#else
-	    usegold = TRUE;
-#endif
-	}
 
 	/* Equivalent of an "ugly check" for gold */
 	if (usegold && !strcmp(word, "eat") && !metallivorous(youmonst.data))
@@ -939,10 +929,7 @@ register const char *let,*word;
 		}
 		if(ilet == def_oc_syms[GOLD_CLASS]) {
 			if (!usegold) {
-			    if (touchstone)
-				You("cannot rub gold on the stone.");
-			    else
-				You("cannot %s gold.", word);
+			    You("cannot %s gold.", word);
 			    return(struct obj *)0;
 #ifndef GOLDOBJ
 			} else if (!allowgold) {