Move all used GHC extensions to Cabal

src/Blog.hs

@@ -1,10 +1,3 @@
-{-# LANGUAGE DeriveDataTypeable  #-}
-{-# LANGUAGE OverloadedStrings   #-}
-{-# LANGUAGE QuasiQuotes         #-}
-{-# LANGUAGE RecordWildCards     #-}
-{-# LANGUAGE ScopedTypeVariables #-}
-{-# LANGUAGE TemplateHaskell     #-}
-
 module Blog where
 
 import           BlogDB

src/BlogDB.hs

@@ -1,11 +1,3 @@
-{-# LANGUAGE DeriveDataTypeable         #-}
-{-# LANGUAGE GeneralizedNewtypeDeriving #-}
-{-# LANGUAGE OverloadedStrings          #-}
-{-# LANGUAGE RecordWildCards            #-}
-{-# LANGUAGE ScopedTypeVariables        #-}
-{-# LANGUAGE TemplateHaskell            #-}
-{-# LANGUAGE TypeFamilies               #-}
-
 module BlogDB where
 
 import           Control.Monad.Reader   (ask)

src/Locales.hs

@@ -1,7 +1,3 @@
-{-# LANGUAGE DeriveDataTypeable  #-}
-{-# LANGUAGE OverloadedStrings   #-}
-{-# LANGUAGE ScopedTypeVariables #-}
-
 module Locales where
 
 import           Data.Data   (Data, Typeable)

src/Main.hs

@@ -1,13 +1,3 @@
-{-# LANGUAGE DeriveDataTypeable         #-}
-{-# LANGUAGE FlexibleContexts           #-}
-{-# LANGUAGE GeneralizedNewtypeDeriving #-}
-{-# LANGUAGE MultiParamTypeClasses      #-}
-{-# LANGUAGE OverloadedStrings          #-}
-{-# LANGUAGE RecordWildCards            #-}
-{-# LANGUAGE ScopedTypeVariables        #-}
-{-# LANGUAGE TemplateHaskell            #-}
-{-# LANGUAGE TypeFamilies               #-}
-
 module Main where
 
 import           Control.Applicative          (optional, pure, (<$>), (<*>))

src/RSS.hs

@@ -1,5 +1,3 @@
-{-# LANGUAGE RecordWildCards #-}
-
 module RSS (renderFeed) where
 
 import qualified Data.Text     as T