2021.08.0

New functionality:

• Added TileProvider.from_qms() allowing to create a TileProvider object from the remote Quick Map Services repository (#71)
• Added support of html_attribution to have live links in attributions in HTML-based outputs like leaflet (#60)
• New Bunch.flatten method creating a flat dictionary of TileProvider objects based on a nested Bunch (#68)
• Added fill_subdomain keyword to TileProvider.build_url to control {s} placeholder in the URL (#75)
• New Bunch.filter method to filter specific providers based on keywords and other criteria (#76)

Minor enhancements:

• Indent providers JSON file for better readability (#64)
• Support dark themes in HTML repr (#70)
• Mark broken providers with status="broken" attribute (#78)
• Document providers requiring registrations (#79)