Allow the interface the server listens on to be configured.

[grs]

It may not always be desirable to listen on all interfaces, which is the default. As an example, by listening instead only on a loopback interface, the server cannot be reached except from within the host it is run on. I believe it would be valuable to allow this to be configured.

PR #2015 is an initial proposal of what that might look like.

[ashwinb]

#2015 is now merged