made the join game screen to get ready for attaching to host and also made a protocol doc

include/game.h

@@ -3,6 +3,9 @@
 #ifndef __game_h__
 #define __game_h__
 
+void init_start_game();
+void render_start_game();
+
 #include <SDL2/SDL.h>
 
 extern SDL_Point mouse_pos;
@@ -17,10 +20,7 @@ extern SDL_Point mouse_pos;
 extern int state;
 
 void start_battle();
-void start_game();
 void show_options();
-void host_game();
-void join_game();
 
 #define GRAB_NEW 2
 #define GRAB_OLD 1