v0.5.0

• The clone command can now use the output file as seed (using --seed-output). If so the output file is first scanned for chunks matching the archive, then found chunks are reorganized in place in the output file. After this other given seeds are processed and finally, if any chunks are still missing, they are now fetched from remote. This also let us avoid write operations when a chunk is already in place in the output.
• Minor chunking performance improvements and various clean ups