Author: Pierre Pichet
remove no more used string 'decfractionof'
http://git.moodle.org/gw?p=moodle.git;a=commit;h=25c9ac33fde10e7feb477ddf0aefd111eb70512e
http://github.com/moodle/moodle/commit/25c9ac33fde10e7feb477ddf0aefd111eb70512e
- 2.0 en [decfractionof,qtype_numerical]