The EventPublisher is the central hub of the PubSub system. It is toughly coupled with much of
stream. Some stream internals were exported exclusively for EventPublisher.
The two Subscribe cases (with or without index) were also awkwardly split between two packages. By
moving EventPublisher into stream they are now both in the same package (although still in different files).
It is critical that Unsubscribe be called with the same pointer to a
SubscriptionRequest that was used to create the Subscription. The
docstring made that clear, but it sill allowed a caler to get it wrong by
creating a new SubscriptionRequest.
By hiding this detail from the caller, and only exposing an Unsubscribe
method, it should be impossible to fail to Unsubscribe.
Also update some godoc strings.
Many of the fields are only needed in one place, and by using a closure
they can be removed from the struct. This reduces the scope of the variables
making it esier to see how they are used.
Otherwise the test will run with exactly the same values each time.
By printing the seed we can attempt to reproduce the test by adding an env var to override the seed
Also remove secretHash, which was used to hash tokens. We don't expose
these tokens anywhere, so we can use the string itself instead of a
Hash.
Fix acl_events_test.go for storing a structs type.