Fuzz testing debug tool

Add code to run a fuzz tester, simulating (more-or-less) random
keyboard mashing. There's no option to turn it on, you need to
set iflags.debug_fuzzer on via a debugger or something along
those lines.

src/cmd.c

@@ -298,6 +298,8 @@ pgetchar() /* courtesy of aeb@cwi.nl */
 {
     register int ch;
 
+    if (iflags.debug_fuzzer)
+        return randomkey();
     if (!(ch = popch()))
         ch = nhgetch();
     return (char) ch;
@@ -942,6 +944,11 @@ wiz_level_change(VOID_ARGS)
 STATIC_PTR int
 wiz_panic(VOID_ARGS)
 {
+    if (iflags.debug_fuzzer) {
+        u.uhp = u.uhpmax = 1000;
+        u.uen = u.uenmax = 1000;
+        return 0;
+    }
     if (yn("Do you want to call panic() and end your game?") == 'y')
         panic("Crash test.");
     return 0;
@@ -4354,6 +4361,29 @@ int NDECL((*cmd_func));
     return FALSE;
 }
 
+char
+randomkey()
+{
+    static int i = 0;
+    char c;
+
+    switch (rn2(12)) {
+    default: c = '\033'; break;
+    case 0: c = '\n'; break;
+    case 1:
+    case 2:
+    case 3:
+    case 4: c = (char)(' ' + rn2((int)('~' - ' '))); break;
+    case 5: c = '\t'; break;
+    case 6: c = (char)('a' + rn2((int)('z' - 'a'))); break;
+    case 7: c = (char)('A' + rn2((int)('Z' - 'A'))); break;
+    case 8: c = extcmdlist[(i++) % SIZE(extcmdlist)].key; break;
+    case 9: c = '#'; break;
+    }
+
+    return c;
+}
+
 int
 ch2spkeys(c, start, end)
 char c;
@@ -5563,6 +5593,8 @@ readchar()
     register int sym;
     int x = u.ux, y = u.uy, mod = 0;
 
+    if (iflags.debug_fuzzer)
+        return randomkey();
     if (*readchar_queue)
         sym = *readchar_queue++;
     else