Proposal: overhaul System.Process

[Bryan O'Sullivan]

Duncan Coutts wrote:

> In Cabal we have two versions:
> 
> usualConvenientVersion :: FilePath -> [String] -> IO String
> 
> moreGeneralVersion :: FilePath -> [String] -> IO (String, ExitCode)

I have written those two functions perhaps twenty times, with the
semantics that Duncan describes, in maybe four different languages.  It
would indeed be very nice to have them in the standard toolbox :-)

	<b