Finish programs for deconvolving the doublets

* deconvolve-doublets.py:  This goes through all the multiplets that
  have been added to a database and appies the shift-subtract method to
  them all.  There are options for using the original "moment" method or
  the new "partition" method for calculating the doublet.

* doublet_utils.py: New function partition_doublet() that finds an
  equivalent doublet to the multiplet by simply partitioning it into two
  at the largest gap between components.