Sort generated subjects alphabetically

This patch sorts all IRI subject declarations that are generated from
an RDFS or OWL input alphabetically.  This has the side effect of
placing all classes first and all predicates after.

src/Data/RDF/Vocabulary/Generator/VocabularyGenerator.hs

@@ -8,7 +8,7 @@ where
 
 import Control.Monad (join)
 import Data.Char (isLower)
-import Data.List (nub)
+import Data.List (nub, sortBy)
 import qualified Data.Map as M
 import Data.Maybe (maybeToList)
 import Data.RDF
@@ -78,7 +78,7 @@ vocabulary graph =
         (prefix, iri) <- M.toList prefixMappings'
         let name = mkName . T.unpack . escape $ prefix <> "NS"
         return $ declarePrefix name prefix iri
-      iriDecls = snd <$> nameDecls
+      iriDecls = fmap snd . sortBy (\x y -> fst y `compare` fst x) $ nameDecls
       irisDecl = declareIRIs $ fst <$> nameDecls
    in sequence $ irisDecl : namespaceDecls <> iriDecls