Add support for various encodings (or pick another)

[rdallman]

currently, gob encoding is used, but a new encoder/decoder is built for each conversion. From xp, and the gob docs themselves, there is a lot of overhead to build the encoder/decoder and it works much faster on streams (see docs: https://golang.org/pkg/encoding/gob/). I believe we're using this because gob can serialize funcs, but feel free to clarify this point. at least, we should build a encoder/decoder and re-use them across conversions to reduce latency, the impact is significant though performance wise. if possible, it may be better to just move to json which is slightly faster but not great (but stdlib), or something else.