* SteamUser is now seperated from SteamFriends, which marely uses it
* added get_user() method which provides instances of SteamUser
* SteamUser instances are weakly cached
* persona state is updated automatically
* added docstring for SteamFriendlist
* added 'ready' event
* renamed 'get_persona_state_value' to 'get_ps'
* SteamFriendlist logger's name is now based on the SteamClient instance name
Rossen Georgiev