BibEdit: fixes wrongly displayed HP changeset bug

* When switching from table to marc view
  cache was created again without adding
  information about the disabled_hp_entries.

* As a result when record was retrieved again
  all HP changesets were displayed as non applied.

* When changing from marc to table view
  gDisabledHpEntries are saved to the cache.

* Displays a message when user has applied a HP
  changeset, has not taken action for all changes
  and tries to switch to marc view.