Case insensitive canonical email addresses

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

@@ -56,7 +56,7 @@ public interface DaoIdentity {
     @Query("SELECT * FROM identity WHERE id = :id")
     EntityIdentity getIdentity(long id);
 
-    @Query("SELECT * FROM identity WHERE account = :account AND email = :email")
+    @Query("SELECT * FROM identity WHERE account = :account AND email = :email COLLATE NOCASE")
     EntityIdentity getIdentity(long account, String email);
 
     @Query("SELECT COUNT(*) FROM identity WHERE synchronize")

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

@@ -651,7 +651,7 @@ public class Helper {
             if (extra.length > 0)
                 a[0] = extra[0];
         }
-        return TextUtils.join("@", a);
+        return TextUtils.join("@", a).toLowerCase();
     }
 
     static void writeText(File file, String content) throws IOException {