[MERGE][0.17] ReST section dividers

[Andrew Bennetts]

John Arbash Meinel wrote:
[...]
> 
> I've always done it this way:
> 
> ==========
> Main Title
> ==========
> 
> Section
> =======
> 
> Subsection
> - ----------
> 
> Subsubsection
> ~~~~~~~~~~~~~
> 
[...]
> 
> This is the sort of thing that is very easy to bike-shed on, so I think we just
> need a "declaration from above" from Martin as to which to use, and then just
> stick with it.

Rather than propose yet another colour of bike shed, I vote for your scheme. :)

-Andrew.