The remove_timestamp and before_timestamp could have 3 different kinds of values with different meanings. That made the code difficult to read and led to some errors. The possibilities were:

• {number} - an actual timestamp the tiles would be compared to
• None - means that the tile should not be considered stale at any time
• 0 - means that the tile should be deleted/refreshed no matter what

I removed the 0 meaning and added remove_all and refresh_all parameters that gets passed into every function where this check is performed. In my opinion that makes the code more understandable.

It also adds a handle_all option to the TileWalker which is used for more complex seeding and cleanup tasks. This option means that all existing tiles will be handled.

This also removes the old style seeding configuration from version 1.0.0. (2011). This makes this PR a breaking change.

This also removes some quirky configuration for the sqlite seed test yaml file by manually waiting 1 second in the test.

And it does fix an error with remove_all and coverage, the reason why I investigated the whole thing in the first place.

Closes #927