* renamed Preferences to "My report preferences"
* renamed Site defaults to "Report defaults"
* rename Change site defaults to "Change report defaults"
* reintroduced Inherit option to Grader preferences - Nicolas was right, it is not possible to implement preference overrides without it with our current get_pref inplementation
* new separate option in plugin selector "Course settings"
* moved displaytype, decimals and aggregation position to "Course settings"
* created new table grade_settings + related functions grade_get/set_preference()
* user report now uses grade_seq class instead of grade_item::fetch_all(); added preloading of grade items into grade_grade instances
* other minor bugfixing/cleanup/improvements
Please note that the Grader report preferences and its defaults must be resaved again - sorry.
