Disabled check that sum of relative grades is 100

[Stivanification]

Hey, first of all thanks for your work on this package! It's very useful to me. However, I don't like the constraint that the sum of the relative grades must sum to 100. Whenever that is the case, one can obtain 100% of the points for the question by simply marking every option as correct. If relative grades are not allowed to assume negative values, that will always be the case. I therefore made the following small changes to the package:

• Allow relative grades to be integers between -100 and 100
• Instead of checking that the sum of the relative grades of all answers is 100, check that the sum of the relative grades of the correct answers is 100

I felt that this would be more reasonable default behavior, so I submitted this pull request.

[Guillaume-Garrigos]

Hi Stefan, (sorry for the late answer)

Thanks for your comments. You are right about negative values, I didn't pay attention to it since I mainly use the option "one anwser only".

Before this weekend (I think) I will inlude this in the code, together with correcting the bug about TexSoup #2