This commit adds two backwards compatible changes to prepare for the next Hugo version, most notable:
* All the `File` methods on `Page` has been deprecated and will give a warning in the next Hugo version. Adjust this by changing `.Dir` to ´.File.Dir` and similar.
* Version the capture shortcode to use the old behaviour for markdown rendering of shortcode inner content.
Bjørn Erik Pedersen
Luc Perkins
Takuya N