Allowed domains consist of `REMARK_URL` second-level domain (or whole IP in case it's IP like `127.0.0.1`) and `ALLOWED_HOSTS`. That is needed to prevent Remark42 from asking arbitrary servers and storing the page title as the comment.PostTitle.
Previous behaviour allowed the caller of the API to create a comment
with an arbitrary URL and learn the title of the page, which might be
accessible to the server Remark42 is installed on but not to the user
outside that network (CWE-918).
* improve TestServer* reliability
* improve TestService_UserReplies reliability
* increase timeout for Test_Main
* improve TestRest_CreateWithPictures readability and reliability
* introduce random port to REST over SSL tests
* tinker TestRest_InfoStreamSince to have more slack before failure
* finalize test errors check unification
* simplify prepServerApp in cmd package tests
* improve TestRest_InfoStreamCancel reliability