fix github issue #905 - ^A vs getpos()

Reported by entrez:  using ^A instead of #retravel after interrupted
travel can pick wrong location if cursor was previously positioned
with movement commands rather than feature targeting because it
won't be starting from the original spot.  Also, ^A after ';' will
just redescribe whatever was examined previously instead of having
the player pick a new spot.

This suppresses cursor positioning from the do-again queue so that
repeating travel or quick-look or other command that needs player
to choose a position will repeat the command but then need to have
a position chosen.  For interrupted #travel, the cursor will already
be placed on the previous destination so that's relatively painless,
but also allows a different destination to be chosen.

It adds iflags.remember_getpos that callers of getpos() could set to
be able to restore the old behavior but none do so far.

Fixes #905

include/flag.h

@@ -196,6 +196,7 @@ struct instance_flags {
     boolean lua_testing;   /* doing lua tests */
     boolean partly_eaten_hack; /* extra flag for xname() used when it's called
                                 * indirectly so we can't use xname_flags() */
+    boolean remember_getpos; /* save getpos() positioning in do-again queue */
     boolean sad_feeling;   /* unseen pet is dying */
     int at_midnight;       /* only valid during end of game disclosure */
     int at_night;          /* also only valid during end of game disclosure */