convert SettingsActivity to kotlin

app/src/main/kotlin/com/simplemobiletools/notes/activities/SettingsActivity.kt

@@ -0,0 +1,43 @@
+package com.simplemobiletools.notes.activities
+
+import android.os.Bundle
+import android.support.v4.app.TaskStackBuilder
+import android.view.View
+import android.widget.AdapterView
+import com.simplemobiletools.notes.R
+import kotlinx.android.synthetic.main.activity_settings.*
+
+class SettingsActivity : SimpleActivity() {
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        setContentView(R.layout.activity_settings)
+
+        setupDarkTheme()
+        setupFontSize()
+    }
+
+    private fun setupDarkTheme() {
+        settings_dark_theme.isChecked = config.isDarkTheme
+        settings_dark_theme_holder.setOnClickListener {
+            settings_dark_theme.toggle()
+            config.isDarkTheme = settings_dark_theme.isChecked
+            restartActivity()
+        }
+    }
+
+    private fun setupFontSize() {
+        settings_font_size.setSelection(config.fontSize)
+        settings_font_size.onItemSelectedListener = object : AdapterView.OnItemSelectedListener {
+            override fun onItemSelected(parent: AdapterView<*>?, view: View?, position: Int, id: Long) {
+                config.fontSize = settings_font_size.selectedItemPosition
+            }
+
+            override fun onNothingSelected(parent: AdapterView<*>?) {
+            }
+        }
+    }
+
+    private fun restartActivity() {
+        TaskStackBuilder.create(applicationContext).addNextIntentWithParentStack(intent).startActivities()
+    }
+}