Add: support of compound disciplines (wait for realizing at db)
Correct: a little correction of user interface at bill page

	modified:   media/css/bill.css
	modified:   ~dev_rating/application/classes/Controller/DeanOffice/Bill.php
	modified:   ~dev_rating/application/classes/Model/Discipline.php
	modified:   ~dev_rating/application/classes/Model/Student.php
	modified:   ~dev_rating/application/views/dean_office/bill.twig