Author: Michael Aherne
MDL-35775 group import Support for groupings
http://git.moodle.org/gw?p=moodle.git;a=commit;h=df3efbfb2cec6dbe7ab278f5267459a1b5eae752
http://github.com/moodle/moodle/commit/df3efbfb2cec6dbe7ab278f5267459a1b5eae752
+ 2.5 en [groupnotaddedtogroupingerror,core_error]
+ 2.5 en [groupingnotaddederror,core_error]
+ 2.5 en [groupaddedtogroupingsuccesfully,core_group]
+ 2.5 en [groupingaddedsuccesfully,core_group]