StreamMatcher constructor

Creates a new StreamMatcher described by description that matches events with matchQueue.

The matchQueue callback is used to implement StreamMatcher.matchQueue, and should follow all the guarantees of that method. In particular:

• If it matches successfully, it should return null and possibly consume events.
• If it fails to match, consume no events and return a description of the failure.
• The description should be in past tense.
• The description should be grammatically valid when used after "the stream"—"emitted the wrong events", for example.

The matchQueue callback may return the empty string to indicate a failure if it has no information to add beyond the description of the failure and the events actually emitted by the stream.

The description should be in the subjunctive mood. This means that it should be grammatically valid when used after the word "should". For example, it might be "emit the right events".