Introduce resources

[bartfeenstra]

#25 shows we want features that require we know more about the resources (pages) we render:

• Created time
• Last modified time (rendered time?)
• Media (images, are other types relevant?)
• Authors

We can create a resource object when starting the rendering process of a new page, give templates read/write access, and destroy it once the process ends.

Can we keep a record of all rendered resources, so static assets such as the sitemap can inspect them?

[bartfeenstra]

Because we cannot call just any function from our template files, without them being registered as filters, this won't work.

However, we can add preprocessing in render.py to build our resource/page object.

[bartfeenstra]

#222 could use this to get the target of the current page in order to render URLs to its translations. Page templates are rendered through dedicated Python functions such as render_entity() and render_entity_type(). Other templated pages are rendered through render_file() as a result of render_tree(), usually after copytree(). Both approaches would need to know the target (an object or the public path string) of the page they are rendering for these locale links to work. For render_file(), when do we know if a file is page? When its name, without extension, is index?