PTAParser.jj: update to include changes from PTAParser.java (fixes #32)

And refresh PTAParser.java (only whitespace changes), correspondingly.

Thanks @muhrik, @VojtechRehak, @Lkorenciak.

prism/src/pta/parser/PTAParser.jj

@@ -154,7 +154,20 @@ public class PTAParser
 			String name;
 			PTA pta;
 			Transition trans;
-			pta = new PTA();
+			LinkedHashSet <String> alphabet = new LinkedHashSet<String>();
+			// Find alphabet
+			n = locationNames.size();
+			for (i = 0; i < n; i++) {
+				ArrayList<astTransition> tt = transitions.get(locationNames.get(i));
+				if (tt == null || tt.isEmpty()) continue;
+				for (astTransition t : tt) {
+					if (t.action != null && !t.action.equals("")) {
+						alphabet.add(t.action);
+					}
+				}
+			}
+			// Create new PTA
+			pta = new PTA(new ArrayList<String> (alphabet));
 			// Add all clocks
 			n = clockNames.size();
 			for (i = 0; i < n; i++)