fix(export): add missing tracker to .torrent (#104)

* fix(export): add missing tracker to .torrent

* fix(export): write fastresume from open file

* fix(export): optimizations

* fix(export): further optimizations

* fix(export): pretty print manifest file

* fix(export): add timestamp to manifest

* fix(export): archive exported files

* chore: order imports

Author: ludviglundgren