Android Samples: add Fragment example (#796)

vtm-android-example/res/layout/fragment_blank.xml

@@ -0,0 +1,12 @@
+<?xml version="1.0" encoding="utf-8"?>
+<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:background="@android:color/white">
+
+    <TextView
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        android:text="@string/empty_fragment_text" />
+
+</RelativeLayout>

vtm-android-example/res/layout/fragment_map.xml

@@ -1,9 +1,10 @@
+<?xml version="1.0" encoding="utf-8"?>
 <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
     android:background="@android:color/white">
 
-    <org.oscim.android.MapView
+    <RelativeLayout
         android:id="@+id/mapView"
         android:layout_width="match_parent"
         android:layout_height="match_parent" />

vtm-android-example/res/menu/fragment_menu.xml

@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="utf-8"?>
+<menu xmlns:android="http://schemas.android.com/apk/res/android">
+
+    <item
+        android:id="@+id/replace_fragment"
+        android:showAsAction="never"
+        android:title="@string/replace_fragment" />
+
+</menu>

vtm-android-example/res/values/strings.xml

@@ -28,5 +28,7 @@
     <string name="warning">Warning</string>
     <string name="startup_message_mbtiles">To run this sample activity, you need an MBTiles database installed on storage.\n\nadb push %s %s</string>
     <string name="exit">Exit</string>
+    <string name="replace_fragment">Replace fragment</string>
+    <string name="empty_fragment_text">This is a fragment to test the back stack behaviour of the map fragment.</string>
 
 </resources>