Two changes have been made to Tor:

1. Set can_complete_circuit to false when the network is disabled, and
don't try to build introduction circuits while can_complete_circuit is
false. This avoids a situation where Tor tries to build introduction
circuits as soon as the network is re-enabled, all the circuits fail,
and then Tor waits 5 minutes before trying to build more.

2. Added a FORGETHS command to the control protocol which clears any
cached client state relating to a specified hidden service. This can be
used to flush state that's likely to be stale before trying to connect
to a hidden service with an unstable network connection.

Support for the FORGETHS command was also added to jtorctl.

Tor has a controller command, TAKEOWNERSHIP, and a configuration option,
__OwningControllerProcess, that work together to ensure Tor shuts down
when the controlling process dies and/or disconnects from the control
port. By using them we can avoid creating runaway Tor processes that
have to be killed with hacks.

Note that some devices (I'm looking at you, Huawei U8110) misreport
connectivity by failing to set EXTRA_NO_CONNECTIVITY and returning true
from ConnectivityManager.getActiveNetworkInfo().isConnected() when
there's no connectivity.

The latest version of libevent (2.0.21-stable) works fine.

Only the ARM binary is included at present. Better control of the Tor
process is needed - it's possible for it to be left running when Briar
exits, and if the cookie file is deleted it's no longer possible to stop
the process.