Remove pcollections-based implementations

pcollections shadowing is no longer required, so remove shadow plugin and
cleanup build scripts.

Author: ilya-g

.gitmodules

@@ -1,4 +0,0 @@
-[submodule "pcollections"]
-	path = pcollections
-	url = https://github.com/ilya-g/pcollections.git
-	branch = dev

README.md

@@ -6,8 +6,6 @@ Immutable collection interfaces and implementation prototypes for Kotlin.
 
 For further details see the [proposal](proposal.md).
 
-Prototype implementation is based on [pcollections](https://pcollections.org/) (Copyright 2015 The pcollections Authors.)
-
 ## What's in this library
 ### Interfaces and implementations
 
@@ -125,11 +123,6 @@ compile 'org.jetbrains.kotlinx:kotlinx-collections-immutable:0.1'
 
 ## Building from source
 
-To initialize submodules after checkout, use the following commands:
-
-    git submodule init
-    git submodule update
-
-Then you can build and install artifacts to maven local with:
+You can build and install artifacts to maven local with:
 
     gradlew build install

build.gradle

@@ -1,10 +1 @@
 ext.JDK_16 = System.getenv("JDK_16")
-
-project('pcollections') {
-    afterEvaluate {
-        compileJava {
-            options.fork = true
-            options.forkOptions.executable = "${JDK_16}/bin/javac"
-        }
-    }
-}

kotlinx-collections-immutable/build.gradle

@@ -6,7 +6,6 @@ buildscript {
     }
     dependencies {
         classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
-        classpath 'com.github.jengelman.gradle.plugins:shadow:1.2.4'
     }
 }
 
@@ -27,24 +26,15 @@ allprojects {
         testCompile "junit:junit:4.12"
     }
 }
-apply plugin: 'com.github.johnrengelman.shadow'
-
-configurations {
-    shadowed
-    compile.extendsFrom(shadow)
-    compile.extendsFrom(shadowed)
-}
 
 dependencies {
-    shadow "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
-    compile "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
-    shadowed project(':pcollections')
+    api "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
 }
 
 project('tests') {
     dependencies {
-        compile project(path: ':kotlinx-collections-immutable', configuration: 'shadow')
-        testCompile 'com.google.guava:guava-testlib:18.0'
+        implementation project(path: ':kotlinx-collections-immutable')
+        testImplementation 'com.google.guava:guava-testlib:18.0'
     }
 }
 
@@ -59,14 +49,6 @@ apply plugin: 'signing'
 apply plugin: 'maven'
 
 
-
-
-shadowJar {
-    classifier = null
-    configurations = [project.configurations.shadowed]
-    relocate 'org.pcollections', 'kotlinx.collections.immutable.internal.org.pcollections'
-}
-
 task sourcesJar(type: Jar) {
     from sourceSets.main.allSource
     classifier "sources"
@@ -83,7 +65,6 @@ task javadocJar(type: Jar, dependsOn: emptyJavadoc) {
 }
 
 artifacts {
-    archives shadowJar
     archives sourcesJar
     archives javadocJar
 }