Protocol versioning
There's a backwards-incompatible change (tagging the number of fds in each Wayland protocol message) that I'd like to make eventually, so ensuring that Waypipe's message protocol has a version number could help avoid any potential unexplained crashes/error messages.
This would entail adding a new message type which provides a integer version number, which is sent by the application-side/server Waypipe instance. If the version does not match exactly, then the display-side/client Waypipe instance should drop the connection, and provide a nice error message.
Adding new message types should not need a protocol version bump, as Waypipe already detects unknown message types and exits if they occur; neither should adding support for more protocols, as Waypipe already muddles its way through unknown protocols.