Add thumbnail support for archive files

[glubsy]

• Generate thumbnails for the most common archive file formats (.zip, .rar, etc.) thanks to the PHP Zip and Rar modules.
• Cache detected file types and errors in a small sqlite3 database whenever the front-end requests incorrect file types or the archive file failed to produce a thumbnail. This saves us the trouble of having to do the same processes all over again whenever a thumbnail is requested in the future.
• Inform the client whenever it assigned an incorrect file type after a thumbnail creation has been attempted.
• The client updates shall use the appropriate preview handler whenever the file type sent back from the back-end has changed from what it was originally detected as (from the file extension alone).
• Add MIME substring to types.json: this is used to better deduce file types from MIME strings returned by the FileInfo module.
• Add optional dependencies to Readme.md.
• Update Changelog.

[glubsy]

This is based on the previous branch at #769 (which is in turn based on #765).

[glubsy]

This should be my last contribution (at least for a while). My master branch includes all my changes against the latest upstream.

Alpha release here.

Hopefully these changes will be merged upstream someday!

[hartmark]

It's sad this good project seems to be abandoned. I'm making a docker instance for my h5ai installation so I get it more portable on other installations.

I will use your repo as base as your PRs have still not been merged :(