This cube models `Files` (pdf document, word processor file, screenshots, etc).

They are stored in the database and fulltext-indexed when possible.

For image files, an adaptor is provided to generate thumbnails (which
are cached in <INSTANCEDIR>/cache/file/thumbnails by default).

Please note that this thumbnail generation adaptor is not meant to be
considered as a "public API" for thumbnail generation. This is just a
simple solution waiting for a proper official API to manage such
features as arbitrary content rendering.


