Store 4 design document

[digitalbuddha]

Issues have been piling up which is no good, some fixes would be easier if we can make breaking changes. Time to fix all the things and plan for a v4 release.

Since we can now break apis and Okio is moving to kotlin (we depend on it for most persister and parsers) it's time we consider a rewrite of Store in kotlin.

Kotlin would give us a cleaner implementation as well as the ability to drop the dependency on rxjava and instead use Coroutines. I believe we can achieve a similar feature set while keeping the library much smaller.

We can then write rxjava bindings for apps that want to continue using RxJava as a public api

[digitalbuddha]

#338 is first addition. Not sure if coroutines will happen but Room definitely will as will conversion to Kotlin since we depend on okio

[Shakezulla57]

Has this started? How does one help with the conversion?