A penalty is added for split configurations which saturate a channel.
Saturation of channels is discouraged as we don't know the fees
beforehand. The penalty is accomplished via an exponential function that
kicks in when the subamount reaches about the total funds available
(this amount is controlled by the parameter EXHAUST_DECAY_FRACTION).
Increases STARTING_CONFIGS to sample more starting configurations.
Reduces CANDIDATES_PER_LEVEL to reduce computational effort.
Increases REDISTRIBUTE.
The time it takes for a typical suggest_split call is about 2 msec a
desktop machine.
