When regenerating navigation lists in a page source file, support a simple way to override the default discovered navigation list by the presence of a .navigation.lst file. A .navigation.lst file would be discovered up the hierarchy, similar to a .template.* page template file, and the first encountered .navigation.lst would take precedence.
Each line is a reference to an artifact, relative to the directory of the corresponding .navigation.lst file, just like references in a template are relative to the original .template.* file location. These artifacts would simply take the place of any artifacts that might have been discovered. The order of the list is maintained.
Once set, the list will be in effect down the hierarchy until overridden by another .navigation.lst. The .navigation.lst may be empty, indicating no navigation items at all.