MT#4145 Change contacts.postcode to varchar.

Can be alphanumeric e.g. in UK/Canada.

db_scripts/diff/15022.down

@@ -0,0 +1,4 @@
+USE billing;
+
+ALTER TABLE contacts 
+  CHANGE COLUMN postcode postcode INT(6) DEFAULT NULL;

db_scripts/diff/15022.up

@@ -0,0 +1,4 @@
+USE billing;
+
+ALTER TABLE contacts 
+  CHANGE COLUMN postcode postcode VARCHAR(16) DEFAULT NULL;