Fix error converting NFA to DFA

I didn't handle epsilon transitions correctly, now I hopefully do.

src/Rextra/Automaton.hs

@@ -64,7 +64,7 @@ allNextStates s =
 
 ndStateToDfaState :: (Ord s, Ord t) => Nfa.Nfa s t -> Nfa.NdState s -> Dfa.State (Nfa.NdState s) t
 ndStateToDfaState nfa ns =
-  let specialTokens = allSpecialTokens $ Nfa.getNdState nfa ns
+  let specialTokens = allSpecialTokens . Nfa.getNdState nfa $ Nfa.epsilonStep nfa ns
   in  Dfa.State { Dfa.transitions       = Map.fromSet (\t -> Nfa.transition nfa t ns) specialTokens
                 , Dfa.defaultTransition = Nfa.defaultTransition nfa ns
                 , Dfa.accepting         = Nfa.accepting nfa ns

src/Rextra/Nfa.hs

@@ -21,6 +21,7 @@ module Rextra.Nfa (
   , NdState
   , getNdState
   -- *** Transitions
+  , epsilonStep
   , transition
   , defaultTransition
   -- *** Running the whole automaton