Templates and Random Documentation Improvements

You can now download Task Fiend templates for you to import into your own instance. I LOVED geeking out on the project/board galleries when I was with Todoist/Trello. I’m excited to reproduce that functionality here, even though I expect I’ll be the only contributor.

I also improved the documentation. It was occasioned by additional description of export functionality, but involved other cleanup including elaborating on how this differs from Todoist, recurrences (some of this documentation was just dead wrong), and a little rearranging on the feature page, which would benefit from further revision because it’s currently a wall of text.