A lot of legal documents have a numbered heading in front of each clause such
as:
12. Idemnification: The corporation has the right to...

In order to get those headings included in the numbering and the TOC and to
use them in the Outline, I would like to apply Heading3 style to the heading
part, but not the rest of the line. Is there any way to define Heading3 such
that there is no line break after it, but the next paragraph starts right
after the heading? (may be even automatically separated by a colon)