Improved circuit management.
Improved circuit management.

pending_circuits is now properly limited and it is now controlled
by the scheduler __init__ parameter "max_pending_factor", which is
used as a multiple of the max_running_circuits configuration parameter
to determine max_pending_circuits:

  max_pending_circuits = max_pending_factor * max_running_circuits.

The default is now 0.5, giving 100 pending circuits in the current default
config,py.  This makes testing much, much, MUCH faster - about 5-10x faster.
I've seen it hit 600+ tests per minute, allowing us to test the entire network
in under five minutes.

hbock/torbel