support for Travel Document

• merged branch "Checkdigit" (release mrz-java-0.4.1)
• document codes "TD", "T", "R" are now supported. They are Travel Documents (Convention '54)

check digit validity in properties

instead of throwing an exception, check digit validity can be retrieved from properties of result object:

• validDocumentNumber
• validDateOfBirth
• validExpirationDate
• [validPersonalNumber]
• validComposite

Fixed final checksum field

• Fixed final checksum field, thanks to Marin Moulinier