Add support for eXtended Channel Flags (XCF). (#48)

Add support for eXtended Channel Flags (XCF). (#48)

Extended channel flags will be controlled by servics via the SVSXCF command.

Settings:
  JOIN_CONNECT_TIME - Number of seconds the user must be online to be able to join
  TALK_CONNECT_TIME - Number of seconds the user must be online to be able to talk on the channel
  TALK_JOIN_TIME    - Number of seconds the user must be on the channel to be able to tlak on the channel
  MAX_BANS          - Will let us increase the ban limit for specific channels

1/0 (on/off) options:
  NO_NOTICE         - no notices can be sent to the channel (on/off)
  NO_CTCP           - no ctcps can be sent to the channel (on/off)
  NO_PART_MSG       - no /part messages (on/off)
  NO_QUIT_MSG       - no /quit messages (on/off)
  EXEMPT_OPPED      - exempt opped users (on/off)
  EXEMPT_VOICED     - exempt voiced users (on/off)
  EXEMPT_IDENTD     - exempt users with identd (on/off)
  EXEMPT_REGISTERED - exempt users with umode +r (on/off)
  EXEMPT_INVITES    - exempt users who are +I'ed (on/off)

Special option:
  GREETMSG - A message that will be sent when a user joins the channel
  DEFAULT  - Reset the channel flags back to the default values

-Kobi.