Qt: get progress column from model
Fix downloader progress update callback
Qt: implement all download table columns
Qt: replace percent column by status column
Qt: fix single bitrate must pass episode too
Qt: fix may download the same episode twice
Qt: use D/L dir from settings when downloading
Default network: CBFT
Qt: add added date and elapsed time columns
Qt: add TODO note in `_DownloadItem`
Qt: avg download speed attempt

Should be computed over a greater period than a single segment
and perhaps interpolated.