Added script for downloading videos with ytdl or any of its derivatives.
The script is adapted from one in my rapberry pi setup which serves
videos remotely, and makes some hardcoded assumptions that might not be
the best for all situations.
Added archive script which takes a file and puts a hardlink to it into
an arbitrary archival folder. This means even if the original file is
deleted its data stays on disk because of its hardlinked archive
version.
