template::head::includes -container .. -parts ...
if an included resource is encountered during rendering of the page, it is ignored. The compound resource management is aligned resource flushing (when a compound resource is flushed, it stop shadowing potentially other resources. An additional option could be to add an "-parts" flag to add_link/add_script.
added simple regression test for basic functionality
New functions for improved theming template::head::flush_link -href ... -rel ... template::head::flush_script -src
These functions are the inverse functions of template::head::add_link and template::head::add_script. These functions are required in situations where e.g. different subsites with different themes have different requirements for a style file provide by some application package.