* 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

* Finished topology query.

* Fixed the bug of CI failure and startup failure.

* Add generate indicator and dispatcher about service topology but not test.

* Delete call type from service relation.

* Streaming analysis topology test success.

* Fixed the check style error.

* Fixed the startup failure cause by query protocol.

* Fixed the bug of startup failure.

* Buffer stream.

* Buffer file reader.

* Buffer library performance test and functional test successfully.

* Fixed the code merge mistake.

* SkyWalking's trace receiver implementation.

* SkyWalking's trace receiver implementation.

* Delete collector module.

Add a lot of documents. @peng-yongsheng @hanahmily . Also @hanahmily , the k8 cluster management document and deploy document need you to add.

* Buffer stream.

* Buffer file reader.

* Register start up.

* Service inventory register test success.

* Storage and Persistence.

* Storage config.

* Fixed the CI failure.

Add a new assembly xml file to oap-starter project, and add `oapService.sh/bat`
files to apm-dist project.

Remove `collectorService.sh/bat` scripts from apm-dist project.

# 1447
Use `GET /api/v1/watch/namespaces/{namespace}/pods` api to watch pod's
containerIp which help collector containers to discovery each other.

* Receiver, aggregate, server finished.

* Cluster module implementation finished.