[jvolkman]

I totally forgot about .proto comments. I spent a while re-implementing that [1] for the IntelliJ editor and even longer testing it [2]. Apparently I opened a bug while doing so; is b/33539835 still open?

1: https://github.com/jvolkman/intellij-protobuf-editor/blob/ma... 2: https://github.com/jvolkman/intellij-protobuf-editor/blob/ma...