Loading PBM files with imageio now returns an array of boolean.
This converts the image to uint8 with 0 or 255 values like before.

Loading a PNG image with imageio now returns a 2-channel image instead
of 4 channels with the first three repeated.

meta(deps): add bob dependency, remove duplicates.

See merge request !48

meta [readme]: Add readme to manifest, set content type

See merge request !47

Auto-update pre-commit

See merge request !46

Switch to the new package structure using citools

Closes #24

See merge request !45