Fixed back from activities

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

@@ -23,6 +23,7 @@ import android.app.PendingIntent;
 import android.content.Context;
 import android.content.Intent;
 import android.os.Bundle;
+import android.view.MenuItem;
 import android.view.View;
 import android.widget.Button;
 
@@ -56,6 +57,16 @@ public class ActivityClear extends ActivityBase {
         });
     }
 
+    @Override
+    public boolean onOptionsItemSelected(MenuItem item) {
+        int itemId = item.getItemId();
+        if (itemId == android.R.id.home) {
+            finish();
+            return true;
+        }
+        return super.onOptionsItemSelected(item);
+    }
+
     static Intent getIntent(Context context) {
         return new Intent(context, ActivityClear.class)
                 .addFlags(Intent.FLAG_ACTIVITY_NEW_TASK |