Imagefield Extract

Adds an option to filefields and filefield widget settings to automatically extract the first managed file from the rendered content with an extension allowed in the field settings. Only extracts one file currently, could be changed with a loop.

The widget settings option enables presenting a checkbox to the editor per field instance - 'Automatically extract this field from the rendered content'. If the checkbox is ticked when an entity with that field instance is edited, the file is extracted and set on hook_entity_presave.