#44 Minor refactorings.
#44 Signature for the new Category interface
#44 Return an immutable Category from a Category object.
#44 Getter for immutable categories in CRData
#44 Changed the data store interface.
#44 Test of the eqclasses stuff.
#44 Now the test calls the proper function.
#44 Made the mutators of AttributeStat package-private.
#44 Stub classes for the new design.
#44 Tests basic Category fields
Merge branch 'master' into Issue0044
#44 Updated the types to the new Category class
#44 Refactored the Category classes
#44 Removed dead code from the IDataStore