Adding the xref schema changes from core. I've done a cursory glance through...

Adding the xref schema changes from core. I've done a cursory glance through the xref code. Looks like all inserts should be ok

misc-scripts/xref_mapping/sql/table.sql

@@ -14,12 +14,12 @@ CREATE TABLE xref (
   description                 text,
   source_id                   int unsigned not null,
   species_id                  int unsigned not null,
-  info_type                   ENUM( 'PROJECTION', 'MISC', 'DEPENDENT',
+  info_type                   ENUM( 'NONE', 'PROJECTION', 'MISC', 'DEPENDENT',
                                     'DIRECT', 'SEQUENCE_MATCH',
                                     'INFERRED_PAIR', 'PROBE',
                                     'UNMAPPED', 'COORDINATE_OVERLAP',
-                                    'CHECKSUM'),
-  info_text	              VARCHAR(255),
+                                    'CHECKSUM') DEFAULT 'NONE' NOT NULL,
+  info_text	              VARCHAR(255) DEFAULT '' NOT NULL,
   dumped                      ENUM( 'MAPPED', 'NO_DUMP_ANOTHER_PRIORITY', 'UNMAPPED_NO_MAPPING',
                                     'UNMAPPED_NO_MASTER', 'UNMAPPED_MASTER_FAILED', 
                                     'UNMAPPED_NO_STABLE_ID', 'UNMAPPED_INTERPRO') DEFAULT null,