Deprecate the any-newer task

The difference between `newer` and `any-newer` is confusing people.  It should be possible to infer which behavior to use.

 * if there is no `dest` config, run task with `src` files that are newer than last run
 * if there is a 1:1 mapping between `src` and `dest` files, run task with only those pairs where `src` is newer than `dest`
 * if there is a many:1 mapping between `src` and `dest` files, run task with all `src` files if any one of them is newer than the `dest` file

This can be accomplished with a single `newer` task.  The `any-newer` task can be set as an alias for a while.