Implement Protobuf Extensions

[bydga]

Hi,
we would also need to use functionality "Protobuf Extensions" (https://developers.google.com/protocol-buffers/docs/proto#extensions). I've already implemented this in the protobuf-schema repo bydga@ff72a17.

Could you please guide me, if its also necessary to edit the protocol-buffer repo - and if where should i start looking? I mean the binary serialization in files like https://github.com/mafintosh/protocol-buffers/blob/master/encodings.js? Or would it get integrated "somehow automatically"? :).

[bydga]

I added one more commit (bydga@3c45d2b) which solves my previous question. I propagate the extends into original message's fields so it gets de/serialized properly. What do you think about it? I will add some tests and create a PR..? Plus you have one issue with your last rewrite of parsing imports - https://github.com/mafintosh/protobuf-schema/blob/master/parse.js#L237 this method which is the only one that properly sets the protos_root_dir(via the opts param) is never called - because you just added to module.exports the parse method.

[mafintosh]

Send me a PR with the extensions stuff. It looks good :)

In regards to the imports and moved the read logic to https://github.com/mafintosh/resolve-protobuf-schema which does disk io to resolve the imports (just forgot to remove the unused function from here).

Imports work with latest version of protocol-buffers if you do

var protobuf = require('protocol-buffers/require')
var messages = protobuf('./my-schema.proto')

[bydga]

yes, i know about it, but it still doesnt work :/
https://gist.github.com/bydga/dcea8c3bfa939a02791d

ability to set option "protos_root_dir" (https://developers.google.com/protocol-buffers/docs/proto#other) is really usefull - you dont want to specify relative path in each import, especially when you have more complex folder structure :)