Retain map fragment instance state

Author: Pygmalion69

app/build.gradle

@@ -7,8 +7,8 @@ android {
         applicationId "org.nitri.opentopo"
         minSdkVersion 19
         targetSdkVersion 28
-        versionCode 6
-        versionName "1.2"
+        versionCode 7
+        versionName "1.2.1"
         testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
     }
     buildTypes {

app/src/main/java/org/nitri/opentopo/MapFragment.java

@@ -119,6 +119,7 @@ public static MapFragment newInstance(double lat, double lon) {
     public void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setHasOptionsMenu(true);
+        setRetainInstance(true);
         Configuration.getInstance().setUserAgentValue(BuildConfig.APPLICATION_ID);
     }