a "filters" dictionnary is now use to filter, it can have, for now, filtering on:
- "body": filter only on the body (equivalent to former "search" parameter, but not case sensitive)
- "search": fitler on body + source resource
- "types": allowed types
- "not_types": forbidden types
primitivus now do searching using "search", i.e. source resource is now taken into account (and search is now case insensitive)