* Site templates can replace theme templates
* Integrate test case within test_site/
* Full backwards-compatibility with testcase in test_site
* Refine test case
* Call parent's block in child template for test case
* Check both templates are applied
* Follow testing advice
* Test for 'include' in themes and shortcodes
* Documentation for themes and how to extend them
Co-authored-by: Vincent Prouillet <balthek@gmail.com>