X11 perm_invent positioning

Change the '|'/#perminv final positioning for X11 to be the same
as for curses:  finishing with <escape> leaves the current view,
with <return> resets to unscrolled.

Actually getting ESC and RET to the right place wasn't trivial;
down the rabbit hole and out the other side.  Using yn_function()
to get the #perminv keystrokes is less than ideal.  (curses also
started that way but switched to raw character input for this.)

include/winX.h

@@ -257,6 +257,7 @@ struct xwindow {
 #define YN_NORMAL     0U /* no flags */
 #define YN_NO_LOGMESG 1U /* suppress echo of prompt+response to message window
                           * and dumplog message history */
+#define YN_NO_DEFAULT 2U /* don't convert quitchars to 0 or ESC to q/n/def */
 
 /* Window variables (winX.c). */
 extern struct xwindow window_list[MAX_WINDOWS];