This is the standard gettext function, although slightly optimised.
-#### `urlto($$)`
+#### `urlto($$;$)`
Construct a relative url to the first parameter from the page named by the
second. The first parameter can be either a page name, or some other
destination file, as registered by `will_render`.
+If the third parameter is passed and is true, an absolute url will be
+constructed instead of the default relative url.
+
#### `targetpage($$)`
Passed a page and an extension, returns the filename that page will be