Fix for phpBB3 support + bonus

username_clean
PhpBB3 requires second column (username_clen) with username as table primary key. Yet, config value "mySQLOtherUsernameColumns" is not an option as this value needs to be formated with phpBB custom utf8_clean_string() function which brings letters to lower case, merges nearby spaces and removes invalid UTF8 chatacters.
Due to characters already being limited both in config and in minecraft itself I believe toLowerCaste() will suffice for now.

num_users
Increment users count not to loose those nice statistics!