* Make receiver more effective

* Add Istio test case and all source dispatch in

* Refactor mock data

* FIx rat.

* Support call component.

* Fix ThermodynamicIndicator bug.

* Fix test cases.

* Fix missing calculate in db merging.

* Add codes for debug.

* 1. Fixed elasticsearch bulk process not fresh bug. (#1819)

2. Fixed the bug of source register no queue but wait the end for batch tag.

* Remove debug log, and restore TTL timer for real scenarios.

2. Fixed the bug of agent mock register order.
3. Fixed the bug of all heatmap.

2. Make service relation and endpoint relation to record component id.
3. Delete service mapping indicator.
4. Make service inventory to record mapping service id.
5. Refactor global topology query and service topology query.

Fixed some meta query bugs.

* Set instance attributes into return value.

* Delete unused code.

* Delete the client side endpoint relation indicator.
Fixed the endpoint topology bug.

* Fixed package failure bug.

Using Mongo 2.14.3, we found that :" java. lang. ClassNotFoundException: Can't find MongoDBCollection Method Interceptor",  must use "org.apache.skywalking.apm.plugin.mongodb.v2.MongoDBCollectionMethodInterceptor" to solve this problem.

* Support metrics downsampling.

* Fixed a check style error.

* Alarm query and alarm persistence test.

* Fixed the package error.

* Fixed the bug from topology.

* no message

* Avoid null point exception

* prepare chinese docs.

* Replace v5 changes by a link to 5.x branch. New v6 changelog.

* Finish query doc and fix a missing field in alarm doc.

* Add link to official oal in alarm doc.

* Fix words.

* Fix some doc

* Update README.md

* Update README.md

* Update README.md

* Update README.md

* Fix broken links to the correct page.

* Direct getting started links to the correct doc