Decouple network layer and packet ser/de

[mprudnik]

• [x] tests and linter show no problems (npm t)
• [x] tests are added/updated for bug fixes and new features
• [x] code is properly formatted (npm run fmt)
• [ ] description of changes is added in CHANGELOG.md
• [ ] update .d.ts typings

[tshemsedinov]

Refs: https://github.com/metarhia/Contracts/blob/master/doc/Metacom.md

[mprudnik]

@tshemsedinov updated the naming to match the contract docs. Few remaining questions (comments in code):

• client: how to handle invalid packet?
• client: how to handle missing handler?
• client: should meta be passed to resolved among call/event result?
• server: how to handle missing handler?
• dist: can this serialization/deserialization be reused to refactor client in dist/ folder?

[mprudnik]

@tshemsedinov Storing handler functions in an object is ok if arrow functions are used since this will be bound automatically. Here's sample code with test - https://github.com/mprudnik/metacom/blob/sample-client-test/test/client.js.

[mprudnik]

@tshemsedinov Done most of the requested changes, the remaining questions are only MetaWritable initialization and naming. And of course CHANGELOG and d.ts.

[mprudnik]

@tshemsedinov all change requests resolved.

[mprudnik]

@tshemsedinov In general, having serializers receive data as objects is easier to extend, much more readable (since you know precisely what is what), and makes work with optional fields easier (in cases of stream, and version for call). Here it is done the same - https://github.com/metarhia/metacom/blob/master/lib/streams.js#L134. Why not pass id, name and size as positional arguments, instead of passing those as options object? So although at first sight, this seems redundant:

({ id, name, size, status }) => ({
    type: 'stream',
    id,
    name,
    size,
    status,
  })

it makes future changes easier to have.

[tshemsedinov]

Landed commit rolled back, it changes expected structures, I'll rewrite it later, we can't include it release as of now Work moved here: https://github.com/metarhia/metacom/pull/425