Adjustments for student view layout
.add-grade-preference function added
Added grade preferences fieldset and updated structure

changes for grade preferences and structural changes for better css
presentation
Adjustments to grade preferences list for dev testing
Proper formatting and improvements to grade_preference editor
refinements to grade_preference
Accommodation of calculate_letter_grade for pass_fail calc
Addition of grade_preferences to grade reports
inclusion of grade_preferences for student viewing and management