* Move `load_tera` to `templates`
I don't know if this is a good place for it, conceptually. I'm moving it
there because I need to use it from `templates`, and `templates` can't
depend on `site`, because there's already a dependency in the opposite
direction.
* Load templates in `markdown` filter
This enables the `markdown` filter to handle shortcodes, as long as
those shortcodes don't access any context variables.
Addresses #1350
* Update documentation of `markdown` filter
* Only load templates for `markdown` filter once
* Clarify `markdown` filter documentation
This is a lightly edited version of what @southerntofu suggested.
* Internal links are resolved in tera markdown filter (close#1296#1316)
* Add a test for internal links in markdown filter
Co-authored-by: southerntofu <southerntofu@thunix.net>
* Replace hack for newline support in shortcodes with new hack
* Be a bit more space efficient/accurate with naming
* Boil newline/whitespace shortcode test down to the essentials
* Make sure the new \n and \s chars in old tests are properly represented
* Support markdown templates and shortcodes
* Refactoring .md/.html shortcode behaviour
* Add test for markdown shortcodes
* Add an html output test for markdown based shortcodes
* Add documentation for Markdown based shortcodes
