reporter of changes in list of available packages from repositories

 Daptup is the apt hook which runs automatically within 'apt-get update' or
 'cupt update' and outputs four lists:
  - packages came to archive with this update;
  - new upgradeable packages;
  - changes in "watched" packages (not installed, such packages have to be
   specified in configuration file);
  - outdated packages that have a new install candidate (optionally).