Configure compiler options

Enable Kotlin 1.3.41's new type inference
Warn about deprecated methods in Java

Signed-off-by: Harsh Shandilya <msfjarvis@gmail.com>

app/build.gradle.kts

@@ -1,5 +1,6 @@
 import org.gradle.api.JavaVersion.*
 import org.jetbrains.kotlin.config.KotlinCompilerVersion
+import org.jetbrains.kotlin.gradle.tasks.KotlinCompile
 
 plugins {
     id("com.android.application")
@@ -95,3 +96,16 @@ dependencies {
     androidTestImplementation("androidx.test.espresso:espresso-core:3.3.0-alpha02")
     androidTestImplementation("androidx.test.espresso:espresso-intents:3.3.0-alpha02")
 }
+
+tasks {
+    withType<JavaCompile> {
+        options.compilerArgs.add("-Xlint:unchecked")
+        options.isDeprecation = true
+    }
+    withType<KotlinCompile> {
+        kotlinOptions {
+            jvmTarget = "1.8"
+            freeCompilerArgs += "-Xnew-inference"
+        }
+    }
+}