This change will mean that SilverStripe\Control\Controller will look for its
template in templates/SilverStripe/Control/Controller.ss.
In order to preserve some backwards campatibility, non-namespaced classes
can have the templates stored in any template subfolder, but once you
add a namespace to a class, the namespaced path expression will need to
be a subfolder of <module>/templates or themes/<theme>/templates.
Layout and Content templates are stil supported as special template type,
Includes still functions but is a no-op. Other template subfolders should
not be used.
