Desugar Java 8 language features for ZXing 3.4

Add desugaring support to reverse translate Java 8 language features
in order to use the latest ZXing without having to increase minSdk.

ZXing 3.4 doesn't work on SDK levels below 24 anymore, see:
zxing/zxing#1170

Many thanks to @TheLastProject for showing me the way:
CatimaLoyalty/Android@cbcf1bc

app/build.gradle

@@ -11,6 +11,9 @@ android {
 		versionCode 93
 		versionName '1.48.1'
 
+		// Required for desugaring.
+		multiDexEnabled true
+
 		// It's recommended to set this value to the lowest API level
 		// able to provide all the functionality.
 		renderscriptTargetApi 24
@@ -61,6 +64,13 @@ android {
 		}
 	}
 
+	compileOptions {
+		// To desugar fancy Java features in ZXing 3.4.+ that don't
+		// work on SDK < 24. See:
+		// https://github.com/zxing/zxing/issues/1170
+		coreLibraryDesugaringEnabled true
+	}
+
 	lintOptions {
 		// Because at the time of writing, even the latest version
 		// of RenderScript is raising this error no matter if
@@ -78,15 +88,14 @@ dependencies {
 	}
 	testImplementation 'junit:junit:4.13.2'
 
+	coreLibraryDesugaring 'com.android.tools:desugar_jdk_libs:1.1.5'
 	implementation "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
 	implementation "org.jetbrains.kotlinx:kotlinx-coroutines-android:1.5.2"
 	implementation "com.android.support:appcompat-v7:$support_version"
 	implementation "com.android.support:design:$support_version"
 	implementation "com.android.support:preference-v7:$support_version"
 	implementation "com.android.support:preference-v14:$support_version"
-	// Do NOT upgrade ZXing because newer versions won't work on API < 24
-	// https://github.com/zxing/zxing/issues/1170
-	implementation 'com.google.zxing:core:3.3.3'
+	implementation 'com.google.zxing:core:3.4.1'
 	implementation 'com.github.markusfisch:CameraView:1.9.1'
 	implementation 'com.github.markusfisch:ScalingImageView:1.3.0'
 }

app/src/main/kotlin/de/markusfisch/android/binaryeye/app/BinaryEyeApp.kt

@@ -1,14 +1,14 @@
 package de.markusfisch.android.binaryeye.app
 
-import android.app.Application
+import android.support.multidex.MultiDexApplication;
 import android.support.v8.renderscript.RenderScript
 import de.markusfisch.android.binaryeye.database.Database
 import de.markusfisch.android.binaryeye.preference.Preferences
 
 val db = Database()
 val prefs = Preferences()
 
-class BinaryEyeApp : Application() {
+class BinaryEyeApp : MultiDexApplication() {
 	override fun onCreate() {
 		super.onCreate()
 		db.open(this)