tty: hide cursor unless waiting for user input

Use vi (cursor_invisible) and ve (cursor_normal) to hide and show
cursor, if the terminal supports those.  This way on a slower
connection the cursor doesn't jump all over the place when doing
map or menu updates.

win/tty/getline.c

@@ -79,7 +79,9 @@ hooked_tty_getlin(
     for (;;) {
         (void) fflush(stdout);
         Strcat(strcat(strcpy(gt.toplines, query), " "), obufp);
+        tty_curs_set(1);
         c = pgetchar();
+        tty_curs_set(0);
         if (c == '\033' || c == EOF) {
             if (c == '\033' && obufp[0] != '\0') {
                 obufp[0] = '\0';