Yet more ePub updates

Found that I may have introduced some problems with the ePub in the last update.  Those should hopefully now be fixed.

This has the slightly strange effect of also adding some minor updates to the ePub/azw3 versions of the game that have not yet made it into the PDFs.  Those changes are quite minor, but in the event of confusion, treat the ePub as the definitive version.

Thanks everyone for your support.