Address some build warnings

app/src/main/java/eu/kanade/tachiyomi/data/preference/PreferencesHelper.kt

@@ -4,7 +4,7 @@ import android.content.Context
 import android.content.SharedPreferences
 import android.net.Uri
 import android.os.Environment
-import android.preference.PreferenceManager
+import androidx.preference.PreferenceManager
 import com.f2prateek.rx.preferences.Preference
 import com.f2prateek.rx.preferences.RxSharedPreferences
 import eu.kanade.tachiyomi.R

app/src/main/java/eu/kanade/tachiyomi/ui/reader/ReaderActivity.kt

@@ -138,12 +138,12 @@ class ReaderActivity : BaseRxActivity<ReaderPresenter>() {
     /**
      * Called when the activity is created. Initializes the presenter and configuration.
      */
-    override fun onCreate(savedState: Bundle?) {
+    override fun onCreate(savedInstanceState: Bundle?) {
         setTheme(when (preferences.readerTheme().getOrDefault()) {
             0 -> R.style.Theme_Reader_Light
             else -> R.style.Theme_Reader
         })
-        super.onCreate(savedState)
+        super.onCreate(savedInstanceState)
         setContentView(R.layout.reader_activity)
 
         if (presenter.needsInit()) {
@@ -159,8 +159,8 @@ class ReaderActivity : BaseRxActivity<ReaderPresenter>() {
             else presenter.init(manga, chapterUrl)
         }
 
-        if (savedState != null) {
-            menuVisible = savedState.getBoolean(::menuVisible.name)
+        if (savedInstanceState != null) {
+            menuVisible = savedInstanceState.getBoolean(::menuVisible.name)
         }
 
         config = ReaderConfig()

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

@@ -14,6 +14,6 @@ fun launchUI(block: suspend CoroutineScope.() -> Unit): Job =
 fun launchIO(block: suspend CoroutineScope.() -> Unit): Job =
         GlobalScope.launch(Dispatchers.IO, CoroutineStart.DEFAULT, block)
 
-@UseExperimental(ExperimentalCoroutinesApi::class)
+@OptIn(ExperimentalCoroutinesApi::class)
 fun launchNow(block: suspend CoroutineScope.() -> Unit): Job =
         GlobalScope.launch(Dispatchers.Main, CoroutineStart.UNDISPATCHED, block)

app/src/main/java/eu/kanade/tachiyomi/util/lang/StringExtensions.kt

@@ -44,7 +44,7 @@ fun String.byteSize(): Int {
  * Returns a string containing the first [n] bytes from this string, or the entire string if this
  * string is shorter.
  */
-@UseExperimental(ExperimentalStdlibApi::class)
+@OptIn(ExperimentalStdlibApi::class)
 fun String.takeBytes(n: Int): String {
     val bytes = toByteArray(Charsets.UTF_8)
     return if (bytes.size <= n) {