Implement language switcher (#563)

* Implement language switching using BaseActivity

* Add requested changes

* Cleanup App.kt Imports and add pref_language_key

* Acutally use @string for key

* Use string resource for language preference title

app/src/main/res/values/arrays.xml

@@ -188,4 +188,20 @@
         <item>2</item>
     </string-array>
 
+    <string-array name="languages">
+        <item>@string/system_default</item>
+        <item>@string/english</item>
+        <item>@string/spanish</item>
+        <item>@string/italian</item>
+        <item>@string/portuguese</item>
+    </string-array>
+
+    <string-array name="languages_values">
+        <item>0</item>
+        <item>1</item>
+        <item>2</item>
+        <item>3</item>
+        <item>4</item>
+    </string-array>
+
 </resources>