2020.9.29

Enchancements:

• Caching (#161).
  Using CacheControl, all HTTP requests are now cached for up to 24h with the lockfile package to ensure Thread safety.
  This should lead to faster load and search times.
  The cache may be flushed at any time by going into debug mode.

Updates:

• New button_style parameter to specify the button's style ("default", "primary", "info", "success", "warning", or "danger") (#171).
  This is available in HeaderDescription, OptimadeQueryFilterWidget, and OptimadeSummaryWidget.

Fixes:

• Update button classes for manually specified buttons (#170).
• Better stability for HTTP requests (#170).
• Fix widget layout settings (#170).

Developer:

• Implement and configure flake8 (#161).
• Keep localhost and 127.0.0.1 out of the cache (#161).