- add new flags for the load functions:

- add new flags for the load functions:
  REPO_LOCALPOOL        - create local pool
  REPO_EXTEND_SOLVABLES - extend existing solvables instead of creating new ones
  REPO_USE_LOADING      - replace repodata in state loading
- add repo_add_solv_flags to make repo_add_solv use flags
- make repo_add_solv obey the flags instead of using defaults if this is a subload
- change loadcallback definition to return a boolean, the callback is now
  responsible for the loading
- change repo_write so that the keyfilter can select which repodata to use (hack)
- change pool_addfileprovides to load the complete filelist if needed
- add SEARCH_COMPLETE_FILELIST flag to searches
- add transaction_create_installedmap/transaction_calc_installsizechange