MDL-34397 course_modinfo REVIEW
MDL-34397 Adding the user request cache when static var is not enough
MDL-34397 Save extra DB query since 'enablecompletion' is cached
MDL-34397 Removing references to fields course.modinfo, sectioncache
MDL-34397 Remove ref to nonexisting course.modinfo in MNET auth
MDL-34397 Allow user=-1 in get_fast_modinfo()