whitespace/semicolon rules for whole config file:
o All non-zero amounts of whitespace are equivalent to single space
(aka `all the whitespace has been born equal' ;-)).
o Comments count as whitespace.
o Whitespace has no syntactic signifance (it can only separate lexical
elements).
o Consequence: line ends are no longer treated as `;'s.
o Every declaration must be terminated by an explicit `;' unless
or by a group enclosed in `{' and `}'.
o Introduced struct filter which serves as an external reference
to filter. Using struct symbol for this is unwise since it doesn't
allow extra information attached to the filter and it also forces
all filters to be named.
o Implemented config rule 'filter' which matches either named filter
or an embedded unnamed filter (`{ <filter> }').
o Fixed totally bogus comment at the top of filter.h.
o Added a missing prototype for f_run() to filter.h.
intended to serve as an example of interface pattern list use. As a side
effect, you can disable generating of device routes by disabling
this protocol.
