Publish directory retains old files on publish

[excalamus]

The publish directory can contain files not generated by the most recent publish. This happens when source files are removed between publishes or when html files are manually added. These files will be accessible unless the server has specific rules to exclude them. This may be undesirable behavior.

Thoughts:

• Include in peut-publier options for clearing the publish directory before generation; to delete, whether to ask to delete, to compare generated files versus those in the directory, etc.
• Require users to create the option, either through modifying the library or their server. Document the former as an example of how to extend peut-publier.