Apache Forrest code add

code add
by
NKB
:

New project sitemap extension mechanism. Now it is possible to add
a project sitemap that plugs into the processing at the beginning.
If the requested url is resolved by it, it will serve the file directly.
If the requested url with the extension changed to xml is matched, then
Forrest will use that result as the intermediate format and render it.
This will enable project-specific sitemaps to not collide with future
Forrest updates.