thumbnails "allow_upscale" parameter is not used

[dadaxr]

in config.yaml, the thumbnails.allow_upscale (default to false) parameter is never read (and so does nothing).

This parameter was used in bolt 3 but in bolt 5, the new ImageController used to generate thumbs does not work the same. It actually use the "fit" parameter (see thumbnails filter doc)

It's possible to replicate the same behavior (ie: disallowing upscaling) by using the "m" (max) fit mode.

I thinks we should either

• remove the "allow_upscale" config parameter
• or take it into account in the ImageController to then use the "m" fit mode
• or simply replace this config param by another, like "default_fit_mode: max"

In addition, it seems there are other thumbnails config in config.yaml not used anymore, like :

• quality
• cropping

If I'm right, the doc default setting for thumbnails should be updated.