Add new API for filtering questions, refactoring the options to display
old questions and include subcategories into new
question_bank_search_condition classes. Make the new API pluggable via
local_[pluginname]_get_question_bank_search_conditions.
quiz_question_statistics_stats renamed to question_statistics_calculator
separate class question_statistics used to store calculated stats
and api changed, also code generally cleaned up.
quiz_question_statistics_stats renamed to question_statistics_calculator
separate class question_statistics used to store calculated stats
and api changed, also code generally cleaned up.