We currently just document the fact that convert.exe can interfere with finding
ImageMagick's convert binary. We can solve this with a config option easily once
confit is merged.
This also changes the line endings for fetchart.rst back to Unix.
artresizer.py instances an ArtResizer object that uses internally the PIL; ImageMagick
or a web proxy service to perform the resizing operations.
Because embedart works on input images located on filesystem it requires PIL or ImageMagick, whereas
fetchart is able to do the job with the fallback webproxy resizer.
