url can be over 255 characters so change it to mediumtext

misc-scripts/xref_mapping/sql/table.sql

@@ -81,7 +81,7 @@ CREATE TABLE source_url (
   source_url_id               int unsigned not null auto_increment,
   source_id                   int unsigned not null,
   species_id                  int unsigned not null,
-  url                         varchar(255),
+  url                         mediumtext,
   checksum                    varchar(255),
   file_modified_date          datetime,
   upload_date                 datetime,