A feature/option to define the criterion for the uncork

[subeeshcbabu-zz]

• It would be awesome if this module provides an option to define the criterion to trigger the uncork.

• Lets say, there is a special character (end of stream character) that could trigger the flush/ uncork on the stream, it would so cool, to use this module to solve that use case.

• https://github.com/indutny/cork-stream/blob/master/lib/cork-stream.js#L37 - basically take a user defined/ custom uncork function option to decide to trigger that based on the data written to the stream. process.nextTick(uncork, this);