* Update How-to-release.md
The public gpg file name should be KEYS, not KEY. It will contains other PMCs public key in this file after you export from the gpg tools.
* Move oal tool back into main repo, and fix compile issue.
* Fix two bugs.
* Remove all generated codes.
* Make all oal generated codes out of source control.
* Make mvn compile and package work.
* Fix test cases.
* Make compile right and provide new documents.
* Remove an unnecessary tokens file.
* Update new protocol
* Support new protocol at agent side.
* Fix test case.
* Make backend supports new trace protocol
* Fix tests.
* Make all new services available in gRPC.
* Fix bugs.
* Finish new document for v2 trace protocol.
* Fix wrong version requirement of zk
* Fix trace query bug.
* Find a client side dictionary bug.
* Fix register bugs.
* Fix break doc links.
* Lock oracle and resin plugins version.
* Move resin and oracle plugin to openskywalking
* Restore submodule active.
* Add another submodule active command.
* Remove the wrong test cases in release and fix some doc issues.
* [maven-release-plugin] prepare release v6.0.0-alpha
* [maven-release-plugin] prepare for next development iteration
* Fix some doc