Updated JoinFork to ForkJoin (as used everywhere)

core/pm.mvc

@@ -21,7 +21,7 @@ SimpleClassDiagrams ProcessModel {
     Class Finish : Activity {
         lower_cardinality = 1
     }
-    Class JoinFork : Activity {}
+    Class ForkJoin : Activity {}
     Class Decision : Activity {
         constraint = $
             String function constraint(model : Element, name : String):