MDL-34397 Move course content cache to MUC
MDL-34397 Removing references to course.modinfo
TODO
MDL-34397 Do not access deprecated field course.modinfo

rebuild_course_cache() now supports resetting cache for multiple but not all courses
MDL-34397 Object section_info calculates expensive data on demand only
MDL-34397 dont write to cm_info properties (REVIEW)
MDL-34397 do not write to cm_info properties
MDL-34397 Properties of cm_info are read-only and calculated on request
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()