Add support for serializing using java.io.DataOutput

[cowtowncoder]

Some frameworks use java.io.DataOutput as output target. While it is possible to write a simple wrapper that implements InputStream over given DataOutput, it makes sense to:

1. Implement such wrapper internally, as baseline, for convenience; this will work for all backends
2. Also implement simple non-delegating version for backends for more efficient output

This should be doable for 2.8, esp. part (1).

[cowtowncoder]

Implemented by a simple wrapper so that internally OutputStream functionality is included over DataOutput provided by caller.