Prepare for 0.4.0.M1

Docs tweaking and package info renaming in README.md
Creating a Publisher will in general bind some resources, which means that there will in general be lifecycle management for it as well (e.g. closing the TCP connection to the stock price ticker). The fact that there can be Publishers with implicitly lifecycle (controlled by GC) does not imply that all of them lack a “finished”, “completed” or “terminated” state. We should not mandate the Rx resource model for other implementations.