Feature summary (what you would like to be able to do and where):
Render single line templates except those on some list.

Use case(s) (list the steps that you performed to discover that problem, and describe the actual underlying problem which you want to solve. Do not describe only a solution):
When I preview some articles on plwiki I would like to see text that happens to be in an IPA template, templates for adding lang attributes and such. I wouldn't want an infobox, but infobox is multiline in code, so that should be filtered out.

There is a similar feature in Popups - it just shows code of small templates. Not ideal, not very user friendly.

Note that there are some single-line templates that community might want to hide (like e.g. messages about article nomination, disamb info). This could be specified on some page like Mediawiki: preview-hidden-templates.

Benefits (why should this be implemented?):
It would benefit all readers, it would make some previews much more readable.

It might also benefit editors, we might even use built-in summary API in the Navigation popups if that works well enough in articles.