If we generate arg1, ... parameters but arg0, ... arguments, things go badly.

git-svn-id: svn+ssh://src.earth.threerings.net/narya/trunk@6425 542714f4-19e9-0310-aa3c-eee0fc999fb1

src/main/java/com/threerings/presents/tools/InvocationTask.java

@@ -177,7 +177,7 @@ public abstract class InvocationTask extends GenTask
                 if (buf.length() > 0) {
                     buf.append(", ");
                 }
-                buf.append("arg").append(ii);
+                buf.append("arg").append(ii+1);
             }
             return buf.toString();
         }