Fix UTF-8 decoding problem in gf -server

The package network-2.4.1.1 thoughlessly introduced a backward incompatible
change to the function Network.URI.unEscapeString, see

    f2168b1f89

This also affects the function Network.Shed.Httpd.queryToArguments, which is
used in GFServer.hs.

To remain compatible with older and newer versions of the network package,
we need to stay clear of queryToArguments and unEscapeString. A replacement
function has been added to server/URLEncoding.hs.

src/server/RunHTTP.hs

@@ -4,9 +4,10 @@ import Network.CGI(ContentType(..))
 import Network.CGI.Protocol(CGIResult(..),CGIRequest(..),Input(..),
                             Headers,HeaderName(..))
 import Network.CGI.Monad(runCGIT)
-import Network.Shed.Httpd(initServer,Request(..),Response(..),queryToArguments)
+import Network.Shed.Httpd(initServer,Request(..),Response(..))
 import qualified Data.ByteString.Lazy.Char8 as BS(pack,unpack)
 import qualified Data.Map as M(fromList)
+import URLEncoding(decodeQuery)
 
 data Options = Options { documentRoot :: String, port :: Int } deriving Show
 
@@ -36,13 +37,15 @@ cgiReq root (Request method uri hdrs body) = CGIRequest vars inputs body'
            '?':s -> s
            s -> s
     al = maybe "" id $ lookup "Accept-Language" hdrs
-    inputs = map input $ queryToArguments $ fixplus qs  -- assumes method=="GET"
+--  inputs = map input $ queryToArguments $ fixplus qs  -- assumes method=="GET"
+    inputs = map input $ decodeQuery qs  -- assumes method=="GET"
     body' = BS.pack body
 
     input (name,val) = (name,Input (BS.pack val) Nothing plaintext)
     plaintext = ContentType "text" "plain" []
-
+{-
     fixplus = concatMap decode
       where
         decode '+' = "%20" -- httpd-shed bug workaround
         decode c   = [c]
+-}