Merge pull request #470 from mckalexee/master

Update Subsegment Type Definitions to Include `namespace`

Author: wangzlei

packages/core/lib/segments/attributes/subsegment.d.ts

@@ -9,6 +9,7 @@ declare class Subsegment {
   subsegments?: Array<Subsegment>;
   parent: SegmentLike;
   segment: Segment;
+  namespace?: string;
 
   constructor(name: string);