A bunch of backend work on how backlinks are saved. Backlinks now have a creation date that will persist through saves and minor changes. It's not much of a big deal right now, but I'm hoping it can provide some additional context in the future, to help identify stale tasks for example.
Backlinks are copied to new days on persistent blocks.
Persistent blocks remove lines that are strikethroughed out the next day. That is, if the line is surrounded by ~~, it gets deleted. Will be adding this as a user setting soon.
Small front end rendering fix.