Improve multi-image file format rotation #407
Description
Right now, multi-image file formats are half-parallelised (analyse only). The current method also reads the file multiple times.
Better performance can be managed by pulling a multi-page PDF/TIFF apart first into temp files on disk, analysing and rotating those, and then reassembling into a multi-page format.
Presently I do this outside of this tool but it could be handy to do it inside the tool.