Optimized sync/donwload, improvements

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

@@ -39,6 +39,12 @@ public interface DaoAttachment {
             " WHERE message = :message")
     int getAttachmentCount(long message);
 
+    @Query("SELECT COUNT(id)" +
+            " FROM attachment" +
+            " WHERE message = :message" +
+            " AND NOT available")
+    int getAttachmentDownloadCount(long message);
+
     @Query("SELECT COUNT(id)" +
             " FROM attachment" +
             " WHERE id = :id")