Posts that are part of a series render an additional start and end include in the post layout.
These two includes should get their own panel like on the index or legal page.
This will result in a more consistent look and feel.

Definition of done:
On a post page that is part of a series (0 - n-1) there are three panels.

1. The first panel shows the series_begin include
2. The second panel shows the actual post content
3. The third panel shows series_end include

On a post page that is part of a series and is the last post of that series (n) there are two panels

1. The first panel shows the series_begin include
2. The second panel shows the actual post content

On a post that is not part of a series there is one panel

1. The panel shows the actual post content