removed the namedtuple with columns, now its an ordereddict of dicts
* added the option to rescale the batch components to a fixed number of moles of
  one of the components
* fixed the saving and opening files
* fixed the opening of a new document
* switched completely to objeclistview for the rescale feature in the mainframe
* adapted the file reading and writing functions to accommodate the changes
* modified the rescaling functions in the calculator so that they are returning
  only scaled values
* removed the CheckableListCtrl since it's not needed anymore
a bit o cleanup, removing code that in no longer needed and move around some
functions for better organization