Unsure what it's used for today and also results in the situation that on
some platforms we generate a reporter.log in bare mode, while on others
where spicy is disabled, we do not.
If we want base/frameworks/version loaded by default, should put it into
init-bare.zeek and possibly remove the loading of the reporter framework
from it - Reporter::error() would still work and be visible on stderr,
just not create a reporter.log.
This makes conn.logs a bit prettier (and smaller) because all lines that
do not use a tunnel will now have a "-" instead of the "(empty)" for
tunnel_parents.
The extensions now work with optional types, as well with complex types
(like subrecords). Not returning a record in the ext_func no longer
crashes bro.
The default_ext_func was switched to return void in
cases where no extension revord is defined (was bool).
I also got rid of the offsets in the indices - with the rest of the
implementation, that was not really necessary and made the code more
complex.
