All pages are imported as terminal pages

The importer currently imports all pages as terminal pages. This is not nice. In particular, pages named "start" (by default, configurable) should be mapped to "WebHome" as they are the main page of a namespace.

Further, also for all other pages, it might be nicer to import them as non-terminal pages. This might create conflicts like in DokuWiki it is possible to have both page:start and page but maybe we could detect this situation and keep creating a terminal document in this special case.