Count with timeout trigger

I created an implementation of a trigger that I'd like to contribute, https://gist.github.com/shikhar/2cb9f1b792be31b7c16e

An example application - if a sink function operates more efficiently if it is writing in a batched fashion, then the windowing mechanism + this trigger can be used. Count to have an upper bound on batch size & better control on memory usage, and timeout to ensure timeliness of the outputs.