Reference1 can hold non numerical data in information mode 1 and 2

[Julien Moutte]

The current code will systematically check the reference 1 field to be a valid number with checksum but information mode 1 and 2 specify that this field is freely formatted. Some N43 files will then contain letters.

The check for reference1 should only happen when information mode is set to 3.

[Julien Moutte]

Sorry I meant reference1 (edited).

[Julien Moutte]

Proposed patch providing information mode to transaction constructor. The mode will then be used to decide how the reference1 field should be checked.