curses update

Miscellaenous stuff either groundwork for or noticed while updating
curses status.  The status changes themselves need some more testing.
One or two of the comments refer to that revised status which hasn't
been checked in yet.

win/curses/cursinvt.c

@@ -23,9 +23,13 @@ curses_update_inv(void)
         /* It's not. Re-initialize the main windows if the
            option was enabled. */
         if (iflags.perm_invent) {
-            curses_create_main_windows();
-            curses_last_messages();
-            doredraw();
+            /* [core_]status_initialize, curses_create_main_windows,
+               curses_last_messages, [core_]doredraw; doredraw will
+               call (*update_inventory) [curses_update_inventory] which
+               will call us but 'win' should be defined that time */
+            curs_reset_windows(TRUE, FALSE);
+            /* TODO: guard against window creation failure [if that's
+               possible] which would lead to uncontrolled recursion */
         }
         return;
     }