Upgrade Kotlin (to 1.3), Coroutines, Gradle and Android gradle plugin.

Kotlin:                1.2.71 -> 1.3.50
Coroutines:            0.30.2 -> 1.3.1
Gradle:                4.6    -> 5.4.1
Android gradle plugin: 3.2.1  -> 3.5.0

This brings us down to *one* experimental coroutine API, and we've
opted in to using it in just *one* place.

(The fact that the API to opt-in to using an experimental API in a
specific place is *also* experimental surely will not come back to
bite us later.)

app/build.gradle

@@ -228,14 +228,12 @@ dependencies {
 
     implementation "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
 
-    final coroutines_version = '0.30.2'
-    implementation "org.jetbrains.kotlinx:kotlinx-coroutines-core:$coroutines_version"
-    implementation "org.jetbrains.kotlinx:kotlinx-coroutines-core-common:$coroutines_version" // TODO: hack!
+    final coroutines_version = '1.3.1'
     implementation "org.jetbrains.kotlinx:kotlinx-coroutines-android:$coroutines_version"
 }
 
 buildscript {
-    ext.kotlin_version = '1.2.71'
+    ext.kotlin_version = '1.3.50'
     repositories {
         mavenCentral()
     }
@@ -248,10 +246,9 @@ repositories {
     mavenCentral()
 }
 
-kotlin {
-    experimental {
-        coroutines 'enable'
-    }
+// See https://kotlinlang.org/docs/reference/experimental.html#experimental-status-of-experimental-api-markers
+tasks.withType(org.jetbrains.kotlin.gradle.tasks.AbstractKotlinCompile).all {
+    kotlinOptions.freeCompilerArgs += ["-Xuse-experimental=kotlin.Experimental"]
 }
 
 androidExtensions {

app/src/main/java/eu/kanade/tachiyomi/data/download/Downloader.kt

@@ -14,7 +14,7 @@ import eu.kanade.tachiyomi.source.model.Page
 import eu.kanade.tachiyomi.source.online.HttpSource
 import eu.kanade.tachiyomi.source.online.fetchAllImageUrlsFromPageList
 import eu.kanade.tachiyomi.util.*
-import kotlinx.coroutines.experimental.async
+import kotlinx.coroutines.async
 import okhttp3.Response
 import rx.Observable
 import rx.android.schedulers.AndroidSchedulers

app/src/main/java/eu/kanade/tachiyomi/extension/ExtensionManager.kt

@@ -13,7 +13,7 @@ import eu.kanade.tachiyomi.extension.util.ExtensionInstaller
 import eu.kanade.tachiyomi.extension.util.ExtensionLoader
 import eu.kanade.tachiyomi.source.SourceManager
 import eu.kanade.tachiyomi.util.launchNow
-import kotlinx.coroutines.experimental.async
+import kotlinx.coroutines.async
 import rx.Observable
 import rx.android.schedulers.AndroidSchedulers
 import rx.schedulers.Schedulers

app/src/main/java/eu/kanade/tachiyomi/extension/util/ExtensionInstallReceiver.kt

@@ -7,10 +7,10 @@ import android.content.IntentFilter
 import eu.kanade.tachiyomi.extension.model.Extension
 import eu.kanade.tachiyomi.extension.model.LoadResult
 import eu.kanade.tachiyomi.util.launchNow
-import kotlinx.coroutines.experimental.CoroutineStart
-import kotlinx.coroutines.experimental.Dispatchers
-import kotlinx.coroutines.experimental.GlobalScope
-import kotlinx.coroutines.experimental.async
+import kotlinx.coroutines.CoroutineStart
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.GlobalScope
+import kotlinx.coroutines.async
 
 /**
  * Broadcast receiver that listens for the system's packages installed, updated or removed, and only

app/src/main/java/eu/kanade/tachiyomi/extension/util/ExtensionLoader.kt

@@ -13,8 +13,8 @@ import eu.kanade.tachiyomi.source.CatalogueSource
 import eu.kanade.tachiyomi.source.Source
 import eu.kanade.tachiyomi.source.SourceFactory
 import eu.kanade.tachiyomi.util.Hash
-import kotlinx.coroutines.experimental.async
-import kotlinx.coroutines.experimental.runBlocking
+import kotlinx.coroutines.async
+import kotlinx.coroutines.runBlocking
 import timber.log.Timber
 import uy.kohesive.injekt.Injekt
 import uy.kohesive.injekt.api.get

app/src/main/java/eu/kanade/tachiyomi/util/CoroutinesExtensions.kt

@@ -1,10 +1,10 @@
 package eu.kanade.tachiyomi.util
 
-import kotlinx.coroutines.experimental.*
-import kotlinx.coroutines.experimental.android.Main
+import kotlinx.coroutines.*
 
 fun launchUI(block: suspend CoroutineScope.() -> Unit): Job =
         GlobalScope.launch(Dispatchers.Main, CoroutineStart.DEFAULT, block)
 
+@UseExperimental(ExperimentalCoroutinesApi::class)
 fun launchNow(block: suspend CoroutineScope.() -> Unit): Job =
         GlobalScope.launch(Dispatchers.Main, CoroutineStart.UNDISPATCHED, block)

build.gradle

@@ -7,7 +7,7 @@ buildscript {
         jcenter()
     }
     dependencies {
-        classpath 'com.android.tools.build:gradle:3.2.1'
+        classpath 'com.android.tools.build:gradle:3.5.0'
         classpath 'com.github.ben-manes:gradle-versions-plugin:0.17.0'
         classpath 'com.github.zellius:android-shortcut-gradle-plugin:0.1.2'
         classpath 'com.google.gms:google-services:3.2.0'

gradle/wrapper/gradle-wrapper.properties

@@ -1,6 +1,6 @@
-#Tue Sep 25 08:47:56 CEST 2018
+#Wed Sep 18 21:00:59 EDT 2019
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-4.6-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-5.4.1-all.zip