introduced assert_date_sorted and altered affected tests.
refactored delta implementation
started the delta feature
Fix requires, make specs running
general refactoring and addition of methods collection to rrepository.
simplified complexity computations
refactored complexity calculations
added ability to calculate total complexity of repository
added codehistory and refactored repository to use it
refactored initialization in repository
added source_file collection to repository
added commit collection to repository
added repository and ability to parse to classes