Added some functionality and corrected an error: the importance coefficient should be member of the grade class, not of the competence class

 On branch master
 Changes to be committed:
	modified:   bin/Debug/schoolGradeLogger
	new file:   competence.cpp
	modified:   competence.hpp
	modified:   grade.hpp
	modified:   lesson.cpp
	modified:   lesson.hpp
	modified:   main.cpp