[RFC]: improve behaviour when using as an external component

[Martin Atkins]

Michael Scherer wrote:
> 
> using "standalone yes", then setting the c2s port will have a different
> impact than doing it in the reverse order, and i think this can be quite
> confusing. 
> 
> I am not very keen of having a option that act like some kind of alias
> for 2 other options, it can only lead to confusion.
> 

I'm inclined to agree. I wonder if the following could work:

ClientPort none
ServerPort none

Since "none" is neither an address:port pair, a port number nor an 
absolute path to a UNIX domain socket I don't think it should cause any 
troubles.