Prefer IPv4 by default

"... in case of a single failure shows that for 86% of countries, IPv4 connectivity is more reliable."

https://blog.usejournal.com/national-internet-segments-reliability-survey-df8129b47743

app/build.gradle

@@ -1,7 +1,7 @@
 apply plugin: 'com.android.application'
 apply plugin: 'com.bugsnag.android.gradle'
 
-def getVersionCode = { -> return 1377 }
+def getVersionCode = { -> return 1378 }
 def getReleaseName = { -> return "\"Ziapelta\"" }
 // https://en.wikipedia.org/wiki/List_of_dinosaur_genera
 

app/src/main/java/eu/faircode/email/EmailService.java

@@ -433,7 +433,7 @@ public class EmailService implements AutoCloseable {
             main = InetAddress.getByName(host);
 
             SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(context);
-            boolean prefer_ip4 = prefs.getBoolean("prefer_ip4", false);
+            boolean prefer_ip4 = prefs.getBoolean("prefer_ip4", true);
             if (prefer_ip4 && main instanceof Inet6Address) {
                 for (InetAddress iaddr : InetAddress.getAllByName(host))
                     if (iaddr instanceof Inet4Address) {

app/src/main/java/eu/faircode/email/FragmentOptionsConnection.java

@@ -280,7 +280,7 @@ public class FragmentOptionsConnection extends FragmentBase implements SharedPre
         etTimeout.setText(timeout == 0 ? null : Integer.toString(timeout));
         etTimeout.setHint(Integer.toString(EmailService.DEFAULT_CONNECT_TIMEOUT));
 
-        swPreferIp4.setChecked(prefs.getBoolean("prefer_ip4", false));
+        swPreferIp4.setChecked(prefs.getBoolean("prefer_ip4", true));
         swSslHarden.setChecked(prefs.getBoolean("ssl_harden", false));
     }