Batch detection

[roberttod]

Batches of events sent synchronously can be detected by the uv-api. Some hook to these batches e.g. uv.onBatch(function (batch) {}) could be useful.

Specifically I need this hook in Jolt, i.e. we could just read/write the cookie once in a batch of events rather than constantly reading and writing. This is a real performance bottleneck right now that should be fixed asap (I think Jolt would run in about a third of the time with this enhancement).

@KidkArolis @jhollingworth does this make sense at all? I can provide an example if you like.

[jhollingworth]

When will batches be sent? What's the value in writing on batch time rather than on debounce? Are there alternative approaches you've considered? (I'm not saying this approach is bad, I just want to get a full picture)