Enhancement: Add option to suppress wrapping content with <p></p>

[DavidBiesack]

In some cases involving fine-grained use of Markdown, it is not appropriate to add <p>...</p> wrappers to the output. For example, the OpenAPI Specification uses Markdown for titles/summaries of items in a an OpenAPI doc. When generating HTML from that doc, these Markdown elements end up embedded in non-block contexts such as in <h2>...</h2>. These contexts are not "complete" Markdown documents, and not even block/paragraph constructs. However, Markdown such as text effects (emphasis, bold, links) are used.

I propose an option to simplify the output so that the caller can determine the context in which the Markdown is presented (the caller can wrap the converted text in a span, a div, a header, a paragraph, etc.)