* Avoid creation of map with all archive contents; instead parse packages
while walking though the archive
* Avoid instantiation of std::string in come cases (using std::string_view)
* Reuse libarchive's archive entry when walking though archive
* Use visitor-based database parser in all places to avoid intermediate big
array with all package objects
* Treat an empty archive buffer/file as error as this should never happen
and it is better to fail early than replacing existing data with nothing
* Query error message also when opening archive from file
Martchus