Here is a version of the ddmatch question for Moodle 2.1 where I have added code for restoration of Moodle 1.9 backups and also the code to do xml export/import.
I will also send this code to Andreev Artem and I hope he will upgrade his github account.
Of course it was rather difficult to test retoration of 1.9 backups so all i did was to download a fresh version of Moodle 1.9, install it create some ddmatch questions, create a backup and test it seems to import correctly in Moodle 2.1. So please report if you find problems so that I can fix the bugs.
The code for XML export/import is somewhat not as smart as I wanted it to be because bugs MDL-30135 and MDL-29060 are not yet fixed so I was forced to duplicate some code to make it working.
To install, unzip, verify that the unzipping process has not created an unwanted level of ddmatch subfolder (there should only be a ddmatch folder with all the files and subfolders in it) and replace the question/type/ddmatch subfolder on your moodle server with this one.
Alternatively you can only replace the question/type/ddmatch/questiontype.php file and add the question/type/ddmatch/backup/moodle1 subfolder because i haven't made any change to other files.