rpc: add verbose parameter to invokefunction and invokescript

pkg/vm/invocation_tree.go

@@ -7,6 +7,6 @@ import (
 // InvocationTree represents a tree with script hashes, traversing it
 // you can see how contracts called each other.
 type InvocationTree struct {
-	Current util.Uint160
-	Calls   []*InvocationTree
+	Current util.Uint160      `json:"hash"`
+	Calls   []*InvocationTree `json:"calls,omitempty"`
 }