GetWork notifications over Websocket

[termoose]

Continuously polling getwork for changes (over HTTP or Websocket) is not really desirable and is the only way to get new work for miners at the moment.

I propose having a notifywork method on the websocket RPC, similar to notifyblocks. This starts a subscription on messages that could look something like this (suggestion):

{
	"jsonrpc": "1.0",
	"method": "latestwork",
	"params": [{
		"data": "block_header",
		"target": "some_target"
	}]
}

The object in the params list here is just the object returned from the regular getwork.

[davecgh]

This is a good idea. However, it will require some infrastructure changes in terms of allowing notifications of when block templates are available to propagate and result in sending such notifications.

[dnldd]

Taking this on