Fixed the issue with a duplicated file being closed but not saved, and showing up next time round (closes #264).
Fixed the issue with a duplicated file being closed but not saved, and showing up next time round (closes #264).

mirams/opencor,Fairly/opencor,mirams/opencor,mirams/opencor,Fairly/opencor,Fairly/opencor,mirams/opencor,mirams/opencor,Fairly/opencor,Fairly/opencor