Remove Rx 1.x integration module

Fixes #595

Author: elizarov

binary-compatibility-validator/build.gradle

@@ -16,7 +16,6 @@ dependencies {
 
     testArtifacts project(':kotlinx-coroutines-reactive')
     testArtifacts project(':kotlinx-coroutines-reactor')
-    testArtifacts project(':kotlinx-coroutines-rx1')
     testArtifacts project(':kotlinx-coroutines-rx2')
 
     testArtifacts project(':kotlinx-coroutines-guava')

binary-compatibility-validator/reference-public-api/kotlinx-coroutines-rx1.txt

@@ -7,5 +7,4 @@ Module name below corresponds to the artifact name in Maven/Gradle.
 
 * [kotlinx-coroutines-reactive](kotlinx-coroutines-reactive/README.md) -- utilities for [Reactive Streams](http://www.reactive-streams.org)
 * [kotlinx-coroutines-reactor](kotlinx-coroutines-reactor/README.md) -- utilities for [Reactor](https://projectreactor.io)
-* [kotlinx-coroutines-rx1](kotlinx-coroutines-rx1/README.md) -- utilities for [RxJava 1.x](https://github.com/ReactiveX/RxJava/tree/1.x)
 * [kotlinx-coroutines-rx2](kotlinx-coroutines-rx2/README.md) -- utilities for [RxJava 2.x](https://github.com/ReactiveX/RxJava)

reactive/README.md

@@ -30,7 +30,6 @@ There are several modules in `kotlinx.coroutines` project that are related to re
 
 * [kotlinx-coroutines-reactive](kotlinx-coroutines-reactive) -- utilities for [Reactive Streams](http://www.reactive-streams.org)
 * [kotlinx-coroutines-reactor](kotlinx-coroutines-reactor) -- utilities for [Reactor](https://projectreactor.io)
-* [kotlinx-coroutines-rx1](kotlinx-coroutines-rx1) -- utilities for [RxJava 1.x](https://github.com/ReactiveX/RxJava/tree/1.x)
 * [kotlinx-coroutines-rx2](kotlinx-coroutines-rx2) -- utilities for [RxJava 2.x](https://github.com/ReactiveX/RxJava)
 
 This guide is mostly based on [Reactive Streams](http://www.reactive-streams.org) specification and uses