hamamatsu: Migrate JPEG ops from ops-jpeg
hamamatsu: Drop _openslide_jpeg_file
hamamatsu: Drop unnecessary downsample calculations
hamamatsu: Drop _openslide_jpeg_level
hamamatsu: Drop start_in_file

It is always 0.
hamamatsu: Drop unused dest_offset_[xy]
hamamatsu: Drop unused subtiling code
hamamatsu: Use tile coordinates in cache key
hamamatsu: Stop sorting all_jpegs

It's a short list of large files, so we're only saving a few seeks if
we're saving any.  We're probably not saving any, because the on-disk
order may not match the lexical order of the filenames.  The only benefit
to sorting is to ensure that we scan the JPEGs in a consistent order.
GKeyFile is order-preserving, so we don't need the sort; we'll just use
the order in which the files are listed in the .vms.
hamamatsu: Drop fileno
hamamatsu: Drop various alter egos of tile_{width,height}
hamamatsu: Rename one_jpeg.mcu_starts_count to tile_count
hamamatsu: Record tiles_{across,down} instead of w/h in one_jpeg
hamamatsu: Rename extract_one_optimisation() arguments
hamamatsu: Drop tile_{width,height} from tile
hamamatsu: Rename read_tile() variable
hamamatsu: Drop remaining conditionals guarding tile size hints
hamamatsu: Move add_hamamatsu_ops() into hamamatsu_vms_part2()
hamamatsu: Drop _openslide_jpeg_tile
hamamatsu: Create scale_denom levels in helper function