Author: Jean-Michel Vedrine
MDL-48715 mod_lesson: add a time spent custom completion rule
http://git.moodle.org/gw?p=moodle.git;a=commit;h=d0445cf70d94ba8f128941e2931c7a221ddd9bcd
http://github.com/moodle/moodle/commit/d0445cf70d94ba8f128941e2931c7a221ddd9bcd
+ 2.9 en [completiontimespend,mod_lesson]
+ 2.9 en [completiontimespendgroup,mod_lesson]
+ 2.9 en [notenoughtimespent,mod_lesson]