Add support for bulk-updating multi-line translations

http://manage.dimagi.com/default.asp?146611

@amsagoff this seems like a new feature since the old parser definitely did not support multi-line translations with un-escaped newline characters. Does this seem like a win to you?
i like this pattern - never seen it before. it's a bit of a surprising use of a closure as opposed to taking `lastIndex` in and returning `value`. maybe just because i'm not used to seeing integers used in closures because that doesn't work in python.