Sharing advanced features

[holtwick]

Advanced features:

• [x] Export all related / embedded assets / items
• [ ] Markdown & HTML should add tags in clear names
• [x] HTML metadata like description (comment), keywords (tags), creation dates etc.
• [x] Export multiple files
• [ ] Export embedded according to their local settings, like link, image, alignments, size, title
• [ ] Instead of export allow to directly open the files
• [ ] Create ZIP files
• [ ] Allow uploads? APIs? WordPress?

Originally posted by @holtwick in https://github.com/holtwick/onepile/issues/76#issuecomment-496897511

[holtwick]

Follow up at #116