Display lists in date order rather than filename order

[aaronpk]

With being able to create posts for dates in the past, such as when importing old content or when bringing in older content via PESOS, the filenames will potentially not match the date order.

For example:

• Note created at 7:00pm on the 16th is named 16-1.md.
• New photo is brought in via PESOS from 6:30pm. Filename is created as 16-2.md.

Now the order of the filenames doesn't match the order of the posts.

With a database, I could simply render the lists in date order, so the filename wouldn't really matter at that point.

[aaronpk]

Since 0.1.12 p3k-core is reading lists from the database and sorting by date rather than filename.