bug#31615: 27.0; doc of `uncomment-region(-default)'

[Eli Zaretskii]

> Date: Sun, 27 May 2018 21:20:04 -0700 (PDT)
> From: Drew Adams <drew.adams@oracle.com>
> 
> 1. These two functions should not have the same doc string.  Function
> `*-default' should say what is - the default value of
> `uncomment-region-function'.

Done.

> 2. The doc strings should be much more specific about the behavior, in
> particular wrt ARG.  Apparently the functions do nothing at all if ARG
> is larger than the first sequence of comment chars in the region.
> 
> E.g. for a comment such as this one:
> 
>   ;; foo bar
> 
> (uncomment-region (line-beginning-position) (line-end-position) 3)
> 
> does nothing.  That's not obvious from the doc.

I'm not sure this was the intent of the code.  I'd expect it to remove
the maximum number of comment delimiters it can, not just punt
silently.

> 3. The doc string talks about "comment markers".  What's that?

It means "comment delimiters"; fixed.

> 4. Enhancement request: Provide a way to remove ALL comment chars and
> all whitespace between them, up to the first non-comment char.

Not done.