Command-line prism understands --help switch, as well as -help.

git-svn-id: https://www.prismmodelchecker.org/svn/prism/prism/trunk@1705 bbc10eb1-c90d-0410-af57-cb519fbb1720

prism/src/prism/PrismCL.java

@@ -836,7 +836,7 @@ public class PrismCL
 				sw = args[i].substring(1);
 				
 				// print help
-				if (sw.equals("help") || sw.equals("?")) {
+				if (sw.equals("help") || sw.equals("-help") || sw.equals("?")) {
 					printHelp();
 					exit();
 				}