patch for review: show ghci-related flags in ghci :set, :show packages, :show languages

[Claus Reinke]

Hi Simon,

> I've tested your patches - unfortunately they fail the tests for me. 
> Multi-line commands apparently work via readline, but not when piped into 
> stdin. 

i don't know what you mean? the tests worked on my platform,
and piping from stdin seems to work fine for me. see log below.
could you tell me what exactly your tests say?

claus

$ /cygdrive/c/fptools/ghc/compiler/stage2/ghc-inplace --version
The Glorious Glasgow Haskell Compilation System, version 6.9.20070917

$ cat cmds.ghci
:{
let { x=True
    ; y=()
    }
:}

(x,y)

:{
:browse
  Data.Maybe
:}

:{
:info
  True
  ()
:}

$ cat cmds.ghci | /cygdrive/c/fptools/ghc/compiler/stage2/ghc-inplace --interactive -v0
(True,())
data Maybe a = Nothing | Just a
maybe :: b -> (a -> b) -> Maybe a -> b
isJust :: Maybe a -> Bool
isNothing :: Maybe a -> Bool
fromJust :: Maybe a -> a
fromMaybe :: a -> Maybe a -> a
maybeToList :: Maybe a -> [a]
listToMaybe :: [a] -> Maybe a
catMaybes :: [Maybe a] -> [a]
mapMaybe :: (a -> Maybe b) -> [a] -> [b]
data Bool = ... | True  -- Defined in GHC.Base
data () = ()    -- Defined in GHC.Base
instance Bounded () -- Defined in GHC.Enum
instance Enum () -- Defined in GHC.Enum
instance Eq () -- Defined in GHC.Base
instance Ord () -- Defined in GHC.Base
instance Read () -- Defined in GHC.Read
instance Show () -- Defined in GHC.Show