Tab plugin

[Nantris]

Indentation plugin should indent using whitespace, not margin.

I think that calling it an indentation plugin is sort of strange. I guess perhaps this is how Microsoft Word handles it, but not in response to Tab and Shift+Tab. Those are pretty universally used to insert or remove tab or tab-like whitespace. I think Plate needs a proper indentation plugin that achieves this via whitespace.

This is in addition to the problems with margin more generally - see Margin Considered Harmful

[zbeyens]

I think it's becoming standard since Notion also uses it. A tab plugin is still interesting to do tho.