Treat the first heading as title and remove it from the content

In DokuWiki, there is no separate title of a page but instead, the first heading is used as title. The title is not separately displayed, but a configuration option can be enabled to display titles on links and in indexes. For this reason, well-formatted DokuWiki pages normally start with a heading of level 1 that is the page title. This looks quite strange when it is imported as the title is basically duplicated.

If the first element of an imported document is a heading of level 1, it should be removed and its content should be used as the document's title.