Added mapstats method

1.Save every kill in a list assigned to a client cvar using the getMapStats function that saves this list in the new class MapStats (so b3 will work faster because the plugin will use self functions instead of connect every time to the database)

2. When map ends (EVT_GAME_EXIT) update all players stats in the database
3. Get current map stats from the database for each client in the server
4. "translate" his stats from string to int and insert every index in a list(each index corresponds to a weapon(declared before at findWeapon function)