Split the core reply formatting code out of control_fmt.c into
control_proto.c.  The remaining code in control_format.c deals with
specific subsystems and will eventually move to join those subsystems.

Signed-off-by: David Goulet <dgoulet@torproject.org>

Signed-off-by: David Goulet <dgoulet@torproject.org>

When we tell the periodic event manager about an event, we are
"registering" that event.  The event sits around without being
usable, however, until we "connect" the event to libevent.  In the
end, we "disconnect" the event and remove its libevent parts.

Previously, we called these operations "add", "setup", and
"destroy", which led to confusion.

This is now the responsibility of the mainloop's subsystem initializer.

Closes ticket 30294.

We need a little refactoring for this to work, since the
initialization code for the periodic events assumes that libevent is
already initialized, which it can't be until it's configured.

This change, combined with the previous ones, lets other subsystems
declare their own periodic events, without mainloop.c having to know
about them.  Implements ticket 30293.

Nick Mathewson authored Mar 18, 2019 and David Goulet committed Apr 30, 2019

This is the last remaining place where our tests had mocked
crypto_rand.

Nick Mathewson authored Mar 18, 2019 and David Goulet committed Apr 30, 2019

We had this previously, but we did it differently in different
places. This implementation is pulled from test_prob_distr.c

Fixes bug 30308; bugfix on 0.3.5.1-alpha.

The nodelist_idx for each node_t serves as a unique identifier for
the node, so we can use a bitarray to hold all the excluded
nodes, and then remove them from the smartlist.

Previously use used smartlist_subtract(sl, excluded), which is
O(len(sl)*len(excluded)).

We can use this function in other places too, but this is the one
that showed up on the profiles of 30291.

Closes ticket 30307.

This makes it match control-spec.txt.