download of tei should rewrite links to embedded images on demand

if you download Tagebuch des Grafen Ferdinand Bonaventura I. von Harrach vom Jahre 1697 und 1698 (German Edition) from tglab it is possibe to have the facs images rewritten from textgrid-uris to local paths. tgrep download does not provide this possibility. we need to check if aggregator already allows this rewrite, and how to activate it.