- Changed filter_rule() to add_rule().

- Improved the debug info coming from add_rule().
- Changed add_filter() to parse_rule() and add_filter_file()
  to parse_filter_file().
- Changed get_filter_tok() to parse_rule_tok().
- Made the mflags a uint32.
- Added an extra arg to get_rule_prefix() to indicate if we're
  building the options for transmission or other purposes.
- The 'C' modifier can now be applied to a '-' rule, so it now
  sets a new flag: MATCHFLG_CVS_IGNORE.
- The send_filter_list() and recv_filter_list() functions now handle
  all the logic needed to do the right thing for -C (this used to be
  in main.c).