We need a way to properly shutdown the adapters

[julienw]

Currently drop functions are not called. This is likely because we don't stop the several threads we're running. One way to do this is to make the SHUTDOWN_FLAG public so that every threads can access it. But it wouldn't be nice for adapters that are in separate repositories.

Another way is to use a "stop" method on adapters, that would be called at the right time.

The openzwave adapter badly needs this.

[Yoric]

What's SHUTDOWN_FLAG?

I'll add a stop method.

[julienw]

I was refering https://github.com/fxbox/foxbox/blob/28b7a54d88f8fd3aad527cca335edfccf6cbdf64/src/main.rs#L170