Add ALF, ACN and ARC sentences

[Erksen]

The information for the ALF, ACN and ARC sentences was taken from the "IEC 61162-1 ED6" standard for maritime navigation and radio communication equipment and systems. I am not sure if the syntax of the three classes are correct, but i guess that there wouldn't be much to correct.

[Knio]

thanks, do you have some example sentences that could be added in unit tests?