Made changes to the Velocity_Balance_2 object to allow a vector of directions
(un-normalized) to be passed to it at initialization. These will be used instead
of the steepest descents that are still computed in the class, but only used
where the direction vector contains NO_DATA values. This will NOT work in
parallel, due to the way direction fields are merged. Changes in the driver
script to make this happen. At the time of this commit the objective function is
evaluating to NaN. I'm not sure why. Otherwise, the results of the balance
velocity calculation 'look' promising.