Zola: Per-section page template

[upsuper]

It can be useful if people can use different page template for different section, and subsection can inherit the page template from its parent when such field is lack. Page's template field would override anything.

Probably add a new page_template can do the trick.

[Keats]

Makes sense

Edit: Actually I'm not 100% sure I want to add it now that I think about the interactions between subsections where sub-sub-sub section would get the same page_template as the parent if not filled would be a bit magical imo.
I'll think about it a bit more

[Keats]

Warming up to the idea, especially if you want to mix completely different context like a blog/gitbook etc. Maybe even having per-section themes could be nice

[Keats]

Closed in favour of #397 which is a bit more detailed.