Allow heading to be hidden or title to be interrogated from content

[jonocodes]

Right now the 'title' is rendered into the title tag and as an H1 at the page top.

The user might want to specify their own H1 and then not render the title into the H1.

Also useful for migrating over old readme's that have an H1.

Another option would be to scrape the first H1 in the page and use that in the title tag. Hmmm.