Login process.
Overide this method to add authentication/authorization.
It must return Conf.JSPROOM when login succeeded (no exceptions).
It must return null if login fails.
This class defines a generic Filter.
Extended classes must fill in :
_name, _id and _description Strings in constructor.
Note that jChatBox conf/ folder path is available thanks to XMLConfig.CONFFOLDER static field.
Filter() -
Constructor for class jChatBox.Chat.Filter.Filter