Proposal: Add System.FilePath to base

[Simon Marlow]

Neil Mitchell wrote:

> The documentation for System.FilePath.Windows and Posix are both
> identical to System.FilePath - they export exactly the same API and
> have exactly the same semantics, just tied to either Windows: or
> Posix: properties given in the main one. I'll update the text in these
> to modules
> to make this more clear.

Yes, I understand what these modules do, I was just surprised that the 
documentation for both modules was empty.  I expected to see the same interface 
as System.FilePath.  Why the #ifdef __HADDOCK__ in System/FilePath/Posix.hs?

Also, rather than having 3 copies of System.FilePath, we should have at most 2 
(this is just an implementation issue, of course).

Cheers,
	Simon