CONTRIBUTING.rst formatting and a typo

Merge branch 'fix_tests_encoding' into 'master'

Fix test encoding by setting LANG and LC_ALL to C.UTF-8

Because we don’t want to rely on each projet setting their own variable LC_ALL and LANG in gitlab’s CI preferences.

See merge request !4

Explicitely use the docker runner on some builds

Fix test encoding by setting LANG and LC_ALL to C.UTF-8

ci: Rename the test archive

Suggest adding tests when contributing

Add a CONTRIBUTING file

Correctly handle the nick change inside the virtual channel

Handle forced-join by just sending an invitation

fix #3116

Refactor channel->parting to a new location

Revert "Use ensure_future instead of async"

This reverts commit a4d67ce041f50e0d25e2b47d04cc25bdad86a048.

Fix the broken commit 4388b9c

e2e: Fix some logic in check_list_of_xpath

Use ensure_future instead of async

Remove an unused variable in e2e

Add an other kewl badge

Coverity upload is allowed to fail and is manual. Also name the artifacts

Optimize tcp_socket::on_send by using vector::erase() only once per call

Very little optimization by using a simpler scope_guard when possible

The version with the vector, that can be disabled etc, is “very” slow, so we
use unique_ptr when we don’t need to disable it, and when it only contains
one function

Use expect_unordered in a few more places