save openslide metadata to .dzi files
save openslide metadata to .dzi files

see https://github.com/jcupitt/libvips/issues/137

todo:

- save to zoomify ImageProperties.xml as well?
- any other useful fields?

lovell/libvips,lovell/libvips,leiyangyou/libvips,wishabi/libvips,jcupitt/libvips,leiyangyou/libvips,jcupitt/libvips,leiyangyou/libvips,mcanthony/libvips,leiyangyou/libvips,wishabi/libvips,mcanthony/libvips,mcanthony/libvips,jcupitt/libvips,jcupitt/libvips,lovell/libvips,lovell/libvips,wishabi/libvips,mcanthony/libvips,wishabi/libvips