Improve stream support

[kevinries]

What is this feature about?

Improve stream support.

What needs to be done to implement this feature?

• Handling of backpressure in both directions. If the receiver detects a backlog, the sender must interrupt the transmission and resume it when the receiver's buffer is empty again.
• Error handling. Stop transmission if an error occurs.

What else should we know?

For this feature the weave protocol must be extended.