Fix build with latest diagrams and GHC-8.0.1

Graphics/Diagram/AlgoDiags.hs

@@ -1,4 +1,7 @@
 {-# OPTIONS_HADDOCK ignore-exports #-}
+{-# LANGUAGE TypeFamilies #-}
+{-# LANGUAGE FlexibleContexts #-}
+
 
 module Graphics.Diagram.AlgoDiags where
 

Graphics/Diagram/Plotter.hs

@@ -1,4 +1,6 @@
 {-# OPTIONS_HADDOCK ignore-exports #-}
+{-# LANGUAGE TypeFamilies #-}
+{-# LANGUAGE FlexibleContexts #-}
 
 module Graphics.Diagram.Plotter where