Support a streaming interface

[cpritcha]

You should be able to send a stream of data to a model for processing. Currently we allow passing data via file. A stream of data could be sent over a socket (we can hide this from the user with special loader and saver classes).

[cpritcha]

The flatbuffer interface makes this possible for writing to the stdin of another process since messages are currently length prefixes, We would just need to add the total number of method calls to the beginning of the stdin stream.