Prepare for 0.4.0.M1

Docs tweaking and package info renaming in README.md
Yes it should be in the `Subscription`. Perhaps we solve this by also saying on the `Subscriber` side that it can't have more than 2^63-1 requests outstanding, and if they do then it is an error. The overflow bit is just good software dev ... I don't know we need to talk about overflow, but just specify that a `Subscription` must support an infinite lifecycle of requests ... but at any given time the total outstanding won't be more than 2^63-1.

Thus, if it is incrementing/decrementing it doesn't need to deal with overflow. If it is monotonically increasing, then it will need to deal with overflow, but that is an implementation detail.

Perhaps something like:

- A `Subscriber` MUST NOT request more than 2^63-1 at a time (outstanding or pending).
- A `Subscription` MUST support an infinite number of calls to `request` and MUST support a pending request count up to 2^63-1 (java.lang.Long.MAX_VALUE). If more than 2^63-1 are requested in pending then `Subscription` MUST emit an error to `Subscriber.onError`.