Figure out why breathable chains sometimes run when state is paused.

[tungs]

In breathe.js 0.2.0, in breatheChain, sometimes handleGates is called when the state is paused, and there is no pause gate defined. This generally happens when a pause command propagates through subchains, apparently in these cases it does not suspend their resolution. I don't think this happens in breathe.js 0.1.7, though I would need to verify.

Currently handleGates creates a pause gate, which seems to prevent pausing issues, but this should be unnecessary if the chain is properly paused.