This fails to produce any output (though throws no errors)

**Foo:** bar

Promoted to ticket #533 and assigned to brian

Ticket resolved in 1.0.42

Actually this is correct. Lines at the beginning of a fandoc document which start with ** are considered part of the header and added to fandoc::Doc.meta.

But...

1. that wasn't documented, so I added a section to docLib::Fandoc
2. we don't want that behavior in a Sidewalk comment, so I added a FandocParser.parseHeaders flag

The next version of Sidewalk should disable header parsing for comments.