Proper html display of paragraphs in enumerations

[domna]

Previously, having multiple paragraphs in an enumeration docstring broke the whole build process.
This is necessary for using the iso/xref conversion, since this always introduces a paragraph.
A hotfix was introduced in #52, which just reduces everything to one paragraph and converts links to in-line links, which is a bit cluttered for longer docstrings, see here for an example.

The dev_tools code should be extended such that this displays properly in paragraphs (don't know whether we can still use html items in that case or if we have to tweak the complete html).