• --metadata-json flag to export post properties (motivated by #33, #47)
• Post properties (accessible by --only-if and exported by --metadata-json) now include caption_mentions and tagged_users (motivated by #47)
• More control about retry mechanism which copes with failing connections: Parameter --max-connection-attempts, and possibility to skip retry with a KeyboardInterrupt, i.e. ^C (motivated by #51)