Allowing the disabling of Match/CTF/Miscellaneous Ringslinger HUD elements

Does what it says on the tin. Requested by Lat and Speedwagon, selfishly also desired because of Thokker, open and shut. If 2.1.16 is delayed, might as well get some goodwill-raising zero-effort stuff in there.

src/d_main.c

@@ -1060,10 +1060,11 @@ void D_SRB2Main(void)
if (M_CheckParm("-warp") && M_IsNextParm())
{
const char *word = M_GetNextParm();
-		if (fastncmp(word, "MAP", 3))
+		char ch; // use this with sscanf to catch non-digits with
+		if (fastncmp(word, "MAP", 3)) // MAPxx name
pstartmap = M_MapNumber(word[3], word[4]);
-		else
-			pstartmap = atoi(word);
+		else if (sscanf(word, "%d%c", &pstartmap, &ch) != 1) // a plain number
+			I_Error("Cannot warp to map %s (invalid map name)\n", word);
// Don't check if lump exists just yet because the wads haven't been loaded!
// Just do a basic range check here.
if (pstartmap < 1 || pstartmap > NUMMAPS)