System update - New servers, PHP 7.3, IPv6

We rolled out some behind-the-scenes changes last weekend:

• New servers! They're faster than the old ones.
• Now running on PHP 7.3 for improved performance, reliability, and a few new features.
• Improved security - now using the samesite flag on authentication cookies.
• New servers are IPv6-only! If you're on IPv4, you still have access via our hosting provider's gateway.
• Lots of small tweaks & fixes.

Enjoy the upgrades!