ID-based aligner utility needs to accept multilingual input

[Former user]

Original [issue 54](https://code.google.com/p/okapi/issues/detail?id=54) created by @ysavourel on 2009-04-11T12:57:11.000Z:

When one of the input file of the ID-based aligner is multilingual it should use the language associated with the list rather than the source in both. So for example: EN in PO source in list 1 and FR in PO target in list 2, or FR in PO target in list 1 and EN in PO source in list 2, etc.

[Former user]

Comment [1.](https://code.google.com/p/okapi/issues/detail?id=54#c1) originally posted by @ysavourel on 2009-04-11T13:57:04.000Z:

This is fixed so that if the file in list 2 is multilingual the target entry for the given target language is used. In other words: You cannot use the source part of a multilingual document as the target of the alignment. It has to be either the source of a monolingual document, or one of the targets of a multilingual document.