Add a publish-subscribe subsystem to publish messages about changes to
OR connections.
connection_or_change_state() in connection_or.c and
control_event_or_conn_event() in control.c publish messages to this
subsystem via helper functions.
Move state constants from connection_or.h to orconn_state.h so that
subscribers don't have to include all of connection_or.h to take
actions based on changes in OR connection state. Move event constants
from control.h for similar reasons.
Part of ticket 27167.
The main.c code is responsible for initialization and shutdown;
the mainloop.c code is responsible for running the main loop of Tor.
Splitting the "generic event loop" part of mainloop.c from the
event-loop-specific part is not done as part of this patch.
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.
