small changes to dronescapes_reader. Added initial support for norm/std

files_per_repr_overwrites and and hsv support. Other backports too (opticalflow/ndims)

little fixes and added depth_ufo plus edges_gb

softseg support

little update to the reader

init file update

little updates -- added some pre-baked representations in init file

updated notebook and added basic dronescapes representations

hm