arogue5: fix player's typed responses getting put at the wrong place.

Some sections of code that prompt the user for a string of input were
calling get_str() with cw (the player-visible screen containing the
map), which caused whatever the player typed to get printed starting at
cw's idea of the cursor position, which was usually the Rogue's @-sign.
This corrupted the map.

The problem has been fixed by passing msgw (the message line at the top
of the screen) to get_str(), so the player's typing appears where msgw
thinks the cursor should be, which is in the sensible place right after
the prompt.  Some other get_str() invocations which used hw or stdscr
have been left unmodified.

arogue5/potions.c

@@ -607,7 +607,7 @@ bool is_potion;
 	     p_guess[which] == NULL)
     {
 	msg(terse ? "Call it: " : "What do you want to call it? ");
-	if (get_str(buf, cw) == NORM)
+	if (get_str(buf, msgw) == NORM)
 	{
 	    p_guess[which] = new((unsigned int) strlen(buf) + 1);
 	    strcpy(p_guess[which], buf);