ModulesFile bugfix (shows up when using digital clocks).

git-svn-id: https://www.prismmodelchecker.org/svn/prism/prism/trunk@1868 bbc10eb1-c90d-0410-af57-cb519fbb1720

prism/src/parser/ast/ModulesFile.java

@@ -403,6 +403,12 @@ public class ModulesFile extends ASTElement
 	 */
 	public void tidyUp() throws PrismLangException
 	{
+		// Clear lists that will generated by this method 
+		// (in case it has already been called previously).
+		formulaIdents.clear();
+		constantIdents.clear();
+		varIdents.clear();
+		
 		// Expansion of formulas and renaming
 
 		// Check formula identifiers