NickServ "notes" command, "oset <command>" restriction, fakehost searching.

NickServ "notes" command, "oset <command>" restriction, fakehost searching.

src/nickserv.c (msgtab): New entries for the "notes" command.
  (cmd_notes): New function to show notes for an account.
  (cmd_oset): Check access for subcommands.
  (struct nickserv_discrim): New "fakehostmask" field.
  (nickserv_discrim_create): Set it.
  (nickserv_discrim_match): Check against it.
  (init_nickserv): Register NOTES and OSET KARMA commands.

src/nickserv.help (SEARCH CRITERIA): Mention FAKEHOST and KARMA options.