Changed to use the method described by Potts for calculating krill density.
Added scaling factor to convert from m3 to m2.
Not relevant because there is now a regions definitions file in EV that
contains all false bottom regions.
Extracts the integration by cells for 38 and 120kHz acoustic variables and
saves them in a separate file for each day (too large for a single file).
Currently using 60 days worth of data from 15/1/2003 - 15/03/2003.