Author: Helen Foster
MDL-87218 lang: Import fixed English strings (en_fix)
http://git.moodle.org/gw?p=moodle.git;a=commit;h=90976d6d5a437f9386943d77deecf21c22ef3f41
http://github.com/moodle/moodle/commit/90976d6d5a437f9386943d77deecf21c22ef3f41
+ 5.1 en [plugin_description,format_singleactivity]