Integrate towncrier for the changelog generation

[asvetlov]

Make it mimic the approach used by aiohttp and others.

P.S.
CI will be tuned later.

[webknjaz]

I think, this folder also needs a separate README explaining what to do. GitHub will then render it in the directory view.

[asvetlov]

The idea is good; the README is not mandatory though.
aiohttp doesn't have it; we have instructions in CONTRIBUTING document.
I think it can work for multidict as well.

[webknjaz]

I saw it work here well: https://github.com/tox-dev/tox/tree/master/docs/changelog.

[asvetlov]

If you want to add README here -- you are welcome. In a separate PR.

[codecov]

Codecov Report

Merging #381 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #381   +/-   ##
=======================================
  Coverage   93.49%   93.49%           
=======================================
  Files          10       10           
  Lines         938      938           
=======================================
  Hits          877      877           
  Misses         61       61

---

Continue to review full report at Codecov.

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[rtd-helper]

😭 Failed to visit version page at https://readthedocs.org/dashboard/multidict/version/refactor-changelog/. Please make sure you have enabled GitHub integration in your RTD project.

[rtd-helper]

Failed to launch chrome!
[1107/222437.450896:ERROR:platform_thread_posix.cc(129)] pthread_create: Resource temporarily unavailable (11)
[1107/222437.450948:ERROR:platform_thread_posix.cc(129)] pthread_create: Resource temporarily unavailable (11)
[1107/222437.451180:ERROR:platform_thread_posix.cc(129)] pthread_create: Resource temporarily unavailable (11)
[1107/222437.451281:ERROR:platform_thread_posix.cc(129)] pthread_create: Resource temporarily unavailable (11)
[1107/222437.451321:ERROR:platform_thread_posix.cc(129)] pthread_create: Resource temporarily unavailable (11)
[1107/222437.451613:ERROR:platform_thread_posix.cc(129)] pthread_create: Resource temporarily unavailable (11)
[1107/222437.452269:ERROR:platform_thread_posix.cc(129)] pthread_create: Resource temporarily unavailable (11)
[1107/222437.451646:FATAL:simple_thread.cc(55)] Check failed: success.
#0 0x5567a57cee29 base::debug::CollectStackTrace()
#1 0x5567a5732ee3 base::debug::StackTrace::StackTrace()
#2 0x5567a57476b3 logging::LogMessage::~LogMessage()
#3 0x5567a57a130d base::SimpleThread::StartAsync()
#4 0x5567a41088f7 content::VizProcessTransportFactory::VizProcessTransportFactory()
#5 0x5567a3c1a7f4 content::BrowserMainLoop::BrowserThreadsStarted()
#6 0x5567a4013873 content::StartupTaskRunner::RunAllTasksNow()
#7 0x5567a3c1a1c2 content::BrowserMainLoop::CreateStartupTasks()
#8 0x5567a3c1cf72 content::BrowserMainRunnerImpl::Initialize()
#9 0x5567a9e0c970 headless::HeadlessContentMainDelegate::RunProcess()
#10 0x5567a536e4ff content::ContentMainRunnerImpl::RunServiceManager()
#11 0x5567a536e236 content::ContentMainRunnerImpl::Run()
#12 0x5567a53baacd service_manager::Main()
#13 0x5567a536c541 content::ContentMain()
#14 0x5567a53b99dd headless::(anonymous namespace)::RunContentMain()
#15 0x5567a53b973b headless::HeadlessShellMain()
#16 0x5567a307e218 ChromeMain
#17 0x7f72a635ab97 __libc_start_main
#18 0x5567a307e0aa _start

Received signal 6
#0 0x5567a57cee29 base::debug::CollectStackTrace()
#1 0x5567a5732ee3 base::debug::StackTrace::StackTrace()
#2 0x5567a57ce9b1 base::debug::(anonymous namespace)::StackDumpSignalHandler()
#3 0x7f72ac3cb890
#4 0x7f72a6377e97 gsignal
#5 0x7f72a6379801 abort
#6 0x5567a57cd815 base::debug::BreakDebugger()
#7 0x5567a5747af9 logging::LogMessage::~LogMessage()
#8 0x5567a57a130d base::SimpleThread::StartAsync()
#9 0x5567a41088f7 content::VizProcessTransportFactory::VizProcessTransportFactory()
#10 0x5567a3c1a7f4 content::BrowserMainLoop::BrowserThreadsStarted()
#11 0x5567a4013873 content::StartupTaskRunner::RunAllTasksNow()
#12 0x5567a3c1a1c2 content::BrowserMainLoop::CreateStartupTasks()
#13 0x5567a3c1cf72 content::BrowserMainRunnerImpl::Initialize()
#14 0x5567a9e0c970 headless::HeadlessContentMainDelegate::RunProcess()
#15 0x5567a536e4ff content::ContentMainRunnerImpl::RunServiceManager()
#16 0x5567a536e236 content::ContentMainRunnerImpl::Run()
#17 0x5567a53baacd service_manager::Main()
#18 0x5567a536c541 content::ContentMain()
#19 0x5567a53b99dd headless::(anonymous namespace)::RunContentMain()
#20 0x5567a53b973b headless::HeadlessShellMain()
#21 0x5567a307e218 ChromeMain
#22 0x7f72a635ab97 __libc_start_main
#23 0x5567a307e0aa _start
r8: 0000000000000000 r9: 00007ffc4920a180 r10: 0000000000000008 r11: 0000000000000246
r12: 00007ffc4920b448 r13: 00007ffc4920a428 r14: 00007ffc4920b450 r15: 00007ffc4920a440
di: 0000000000000002 si: 00007ffc4920a180 bp: 00007ffc4920a3d0 bx: 00007ffc4920a428
dx: 0000000000000000 ax: 0000000000000000 cx: 00007f72a6377e97 sp: 00007ffc4920a180
ip: 00007f72a6377e97 efl: 0000000000000246 cgf: 0000000000000033 erf: 0000000000000000
trp: 0000000000000000 msk: 0000000000000000 cr2: 0000000000000000
[end of stack trace]
Calling _exit(1). Core file will not be generated.

TROUBLESHOOTING: https://github.com/GoogleChrome/puppeteer/blob/master/docs/troubleshooting.md

[asvetlov]

@webknjaz what are the rtd comments?
Why they are here? And why is this crappy stacktrace from chrome?

[webknjaz]

@asvetlov probably because you forgot to add rtd-bot to the RTD project as a maintainer. This is an integration that shows previews of docs changes for PRs.

[asvetlov]

I did not add this bot to the project; I have no idea what is the bot for