Move workflow event to history

Author: cschleiden

core/workflowevent.go

@@ -0,0 +1,10 @@
+package history
+
+import "github.com/cschleiden/go-workflows/core"
+
+// WorkflowEvent is a event addressed for a specific workflow instance
+type WorkflowEvent struct {
+	WorkflowInstance core.WorkflowInstance
+
+	HistoryEvent Event
+}