Handle chapters and Titlepages - optimize usage of LaTeX document classes

[bwl21]

Depending on the chosen Documentclass, the handling of Titlepage and Chapter levels:

• article: no chapters, no part
• book: pandoc - option --chapters and option --part if pandoc supports it

Pandoc by default shall use book

In any case we need to fix \maketitle such that it does not cause a new page. Otherwise, Frontmatter would not work.

Final solution would be to remove usage of \maketitle at all. In this case the pandoc meta data needs to be handled by default.latex ...