Don't URL encode path components (#2505)

Fixes #2467

After dhall-lang/dhall-lang#581 the standard
requires implementations to not do anything special with respect to
URL encoding.  In other words, a conforming implementation:

- Should not URL-encode path components when parsing imports from Dhall
  source code

- Should not URL-encode path components when resolving those same
  imports

The user can still specify an import that uses URL encoded path
components, but the implementation does not give them any special
treatment.  It just blindly forwards those path components undisturbed.

Before this change, the Haskell implementation of Dhall was correctly
handling the first part (not url encoding path components at parse
time) but was still incorrectly handling the second part (because it
would URL encode path components at import resolution time).  This
change fixes that.

dhall/dhall.cabal

@@ -253,7 +253,6 @@ Common common
         transformers                >= 0.5.2.0  && < 0.7 ,
         unix-compat                 >= 0.4.2    && < 0.7 ,
         unordered-containers        >= 0.1.3.0  && < 0.3 ,
-        uri-encode                                 < 1.6 ,
         vector                      >= 0.11.0.0 && < 0.14
 
     if flag(with-http)

dhall/src/Dhall/URL.hs

@@ -7,10 +7,8 @@ import Data.Text (Text)
 
 import Dhall.Syntax (Directory (..), File (..), Scheme (..), URL (..))
 
-import qualified Network.URI.Encode as URI.Encode
-
 renderComponent :: Text -> Text
-renderComponent component = "/" <> URI.Encode.encodeText component
+renderComponent component = "/" <> component
 
 renderQuery :: Text -> Text
 renderQuery query = "?" <> query