Update tengo vendor and load the stdlib. Fixes #789 (#792)

vendor/github.com/d5/tengo/objects/count_objects.go

@@ -0,0 +1,31 @@
+package objects
+
+// CountObjects returns the number of objects that a given object o contains.
+// For scalar value types, it will always be 1. For compound value types,
+// this will include its elements and all of their elements recursively.
+func CountObjects(o Object) (c int) {
+	c = 1
+
+	switch o := o.(type) {
+	case *Array:
+		for _, v := range o.Value {
+			c += CountObjects(v)
+		}
+	case *ImmutableArray:
+		for _, v := range o.Value {
+			c += CountObjects(v)
+		}
+	case *Map:
+		for _, v := range o.Value {
+			c += CountObjects(v)
+		}
+	case *ImmutableMap:
+		for _, v := range o.Value {
+			c += CountObjects(v)
+		}
+	case *Error:
+		c += CountObjects(o.Value)
+	}
+
+	return
+}