Please be sure to include:

* what OS you are developing on (Linux or macOS, including the version)

* for macOS, what version of Xcode you are using (`xcodebuild -version`),
  for Linux, what version of Swift (`swift --version`)

* what version of Swift is your code set to compile with (i.e. from project
  settings, etc.)

* what branch/tag of SwiftProtobuf you are using (1.0.0, etc.)

* if you are getting compile errors, please be sure include all errors/warnings,
  sometimes the error before the one you are stuck on is important.

* lastly, if it all possible, provide a snippet of `.proto` and/or source
  that shows the problem.

Thank you!

Add a template for new issues.
Add a template for new issues.

Per: https://help.github.com/articles/creating-an-issue-template-for-your-repository/
