perf: Websocket message aggregation

[mmeeks]

It is my suspicion that if we spin the main-loop with a 1ms sleep (as we do for message slurping) that we surrender our time-slice to the kernel - and that on a loaded system this can make COOL loose out performance-wise.

And we do this quite a lot I think; so we should try to aggregate many more messages into a single message over the top of the existing Websocket channel.

This requires a bit of JS work - and some extra framing inside the websocket messages themselves: with size + bytes etc. I guess. Possibly it will also break things - and force us to use 'Promise' methods on blobs in JS - which may exacerbate the problem we try to fix (ARGH! ;-) but possibly we can make this work.

I imagine jamming many tiles into one websocket message would be good, and/or reading the protocol to work out where we can unify other common messages - eg. state-changed into a single message perhaps saving protocol bandwidth as well as number-of-websocket-messages :-)

Thanks!