Improve usability of Grade Display Type

Go to gradebook setup. Create a new grade item. Click on show more under grade item. For all grade types: Select the grade type. In case of text or none (none is only available in add category view): Check that Grade display type and Overall decimal places  are disabled In case of value or scale: Check that Grade display type and Overall decimal places  are enabled. Additionally, check that the grade display type help has now detailed descriptions for all options. Proceed with adding a new grade category. Go to the grade category settings in the site administration (Site administration > Grades > Grade category settings). Add more available aggregation types. Select all of them. Enter the course and go back to the Gradebook setup under the administration menu / The settings cog for the course. On the Gradebook setup screen click on the "Add category" button at the bottom. Change the aggregation in the "Grade category" section. Under the Category total section click the "Show more..." link. Change the Grade type. Check that when the grade type is changed to scale that the max and min grade are disabled. Check that when the grade type is changed to text that the max and min grade are disabled, as well as grade to pass, and grade display type. Check that clicking the grade display type help shows an explanation for each grade type, and not just the name.