Allow prefix for thumbnails (or/and expand wizard for it) #139
Description
If "put everything in a folder" is chosen, everything is put into a page-bundle and the images are put into "images". Thumbnail does not search in /images but in the root folder of the index.md.
I think there should be a setting to include a prefix to the thumbnail-path. A bit like
exports.image_path_prefix = "" # Leave empty to look into the root folder of the posts *.md
This way this could be set individually.
Another (or additional) option could be to ask within the wizard:
"When putting posts into page-bundles, ask if the images-prefix should be set to look up images. If answer to 'put into page-bundles' is no, don't ask about prefix."