Remove remnants of screen recording stuff

Most of the code was already commented out, and those comments were
removed in earlier commits, but this removes all recording variables
from Game and simplifies the game-gamestate handling in main.cpp a
little bit.

desktop_version/src/Game.cpp

@@ -148,11 +148,6 @@ void Game::init(void)
     press_left = 0;
 
 
-    recording = 0;
-    recordinit = false;
-    playbackfinished = false;
-    recordstring = "";
-
     advancetext = false;
     pausescript = false;
     completestop = false;