Add networking to game engine / add multiplayer chess

src/game_chess.h

@@ -25,6 +25,20 @@
 
 #include "game_base.h"
 
-int chess_initialize(GameData *game);
+/*
+ * Initializes chess game state.
+ *
+ * If `init_data` is non-null, this indicates that we were invited to the game.
+ *
+ * If we're the inviter, we send an invite packet after initialization. If we're the
+ * invitee, we send a handshake response packet to the inviter.
+ *
+ * Return 0 on success.
+ * Return -1 if window is too small.
+ * Return -2 on network related error.
+ * Return -3 on other error.
+ */
+int chess_initialize(GameData *game, const uint8_t *init_data, size_t length);
 
 #endif // GAME_CHESS
+