new directory structure

[yjbanov]

This is a proposal and a step towards a new directory structure.

Motivation

Our current directory structure is a Dart pub project mixed with things that have nothing to do with it, such as contrib, pub-server.go, boilerplate (license, readme, etc). It also does not support feature incubation. All code goes into the core directories and it is hard to tell unstable parts from the stable parts. We are also planning to develop sample apps showcasing Streamy features and there is no logical place for them in the repo.

Proposal

.
├ streamy/ - contains core streamy libraries (in pure pub format)
├ contrib/ - contains useful utilities that help with project operations
├ labs/ - where new major features are incubated
├ examples/ - demo apps
├ LICENSE, README.md, VERSION

We should be mindful about what we put into the root folder.