group commands (remove member, leave group, delete group) (#87)

* remove group member

* leave group, fix remove member, tests for leave group/remove member

* delete group with test

* prevent contact deletion error when it is a group member

* support inviting the group member who left or was removed

* use small retry interval in the tests

* test multiline outputs

.github/workflows/build.yml

@@ -4,6 +4,7 @@ on:
   push:
     branches:
       - master
+      - v4
     tags:
       - "v*"
   pull_request: