v0.4.0

Added

• The seven tools that change nothing publish readOnlyHint: true:
  list_feeds, get_feed, list_entries, search_entries,
  list_categories, export_opml and get_stats. A gateway uses the
  annotation to decide whether an invalid optional argument, such as the
  feed_id: 0 some clients send as a placeholder, may be dropped or must
  refuse the call (crunchtools/trentina#335). read_entry is not
  annotated, because it marks the entry read.