Remove SubscriptionReceiveChannel

[deva666]

#283 Issue says that SubscriptionReceiveChannel should be removed, so this PR is a breaking change. Not sure if this is wanted?

[elizarov]

That is Ok. It is supposed to be breaking change in the source. However, for binary compatibility we need to keep old SubscrpitonReceiveChannel interface (as deprecated), keep old openSubscription function (as deprecated/hidden), so new openSubscription will probably have to use a different @JvmName.

Also, can you please rebase your changes onto the latest develop branch.

[deva666]

@elizarov not sure how you can apply JvmName annotation in this case. And of course, there can't be two functions with different return types. If we deprecate the old openSubscription function can the new one be named differently, something like openReceiveChannel ?

[elizarov]

Hm... I checked. Indeed, I cannot seem to find a way to preserve binary compatibility when changing return type. This is bad: https://youtrack.jetbrains.com/issue/KT-23750

[elizarov]

I've found a way to preserve binary compatibility. Merged this PR into develop.