Interpolate "- Press ENTER to Teleport -" prompt

This is only really noticeable in slowmode, but if you're playing in
slowmode it'll be pretty smooth.

desktop_version/src/Game.cpp

@@ -168,6 +168,7 @@ void Game::init(void)
 
     activetele = false;
     readytotele = 0;
+    oldreadytotele = 0;
     activity_lastprompt = "";
     activity_r = 0;
     activity_g = 0;