Player extra info

[8dcc]

Changes:

• Add extra_player_info_t struct and player_extra_info global variable.
• Add game_id enum and this_game_id global variable.
• Add get_cur_game function to util.c
• Add new method for is_friend depending on the current game.

[8dcc]

Forgot to credit @oxiKKK for his help and knowledge.