by slashrsm: Add image for generic files - part of Media module (commit fe4c5751).
by slashrsm: Move icon to the icons subfolder.
by slashrsm: Copy icons to public:// on install.
by slashrsm: Add thumbnail() to MediaTypeInterface.
by slashrsm: Make media_entity_copy_icons() reusable for other modules.
by slashrsm: Add Media as argument on thumbnail().
by slashrsm: Add thumbnail base field.
by slashrsm: Add media library view mode.
by slashrsm: Add newline.
Merge pull request #20 from slashrsm/library

Add thumbnail API