Remove StreamOutput trait, it was inconsistent with the rest of the design
Removed package docs, they are outdated and the readme replaces them
Remove extra type param on Connector, since it never changes its elements
Add variants for most methods in SourceOps.
Add lots of scaladocs.
trait StreamComponent should not be package-private since it's exposed in RunningStreamComponent, which is public
Remove StreamConsumer, it's no longer in use