The old implementation did some funky out-of-order lexing, and
tended to parse every port twice if the %d-%d pattern didn't match.

Closes ticket 28853.

In dirauth:
  * bwauth.c reads and uses bandwidth files
  * guardfraction.c reads and uses the guardfraction file
  * reachability.c tests relay reachability
  * recommend_pkg.c handles the recommended-packages lines.
  * recv_descs.c handles fingerprint files and processing incoming
    routerinfos that relays upload to us
  * voteflag.c computes flag thresholds and sets those thresholds on
    routerstatuses when computing votes

In control:
  * fmt_serverstatus.c generates the ancient "v1 server status"
    format that controllers expect.

In nodelist:
  * routerstatus_fmt.c formats routerstatus entries for a consensus,
    a vote, or for the controller.

(from #20874 fix)

I am very glad to have written this script.

This commit won't build yet -- it just puts everything in a slightly
more logical place.

The reasoning here is that "src/core" will hold the stuff that every (or
nearly every) tor instance will need in order to do onion routing.
Other features (including some necessary ones) will live in
"src/feature".  The "src/app" directory will hold the stuff needed
to have Tor be an application you can actually run.

This commit DOES NOT refactor the former contents of src/or into a
logical set of acyclic libraries, or change any code at all.  That
will have to come in the future.

We will continue to move things around and split them in the future,
but I hope this lays a reasonable groundwork for doing so.

or.h should really include only the minimum of stuff from or/*,
common/*, and lib/*.

I was expecting this to be much worse.

This will yield different error codes for transient and permament
errors. Furthermore, Tor will give human readable error
messages to controller.

When the fascist_firewall_choose_address_ functions don't find a
reachable address, set the returned address to the null address and port.

This is a precautionary measure, because some callers do not check the
return value.

Fixes bug 24736; bugfix on 0.2.8.2-alpha.

Also make IPv6-only clients wait for microdescs for relays, even if we were
previously using descriptors (or were using them as a bridge) and have
a cached descriptor for them.

But if node_is_a_configured_bridge(), stop waiting for its IPv6 address in
a microdescriptor, because we'll never use it.

Implements #23827.