First finished draft of database model

src/BachelorDegree.java

src/BachelorSemester.java

src/Calcuable.java

src/Course.java

src/CourseType.java

src/CoursesOfStudy.java

src/Enrollment.java

src/ExamType.java

src/Gender.java

src/Lecturer.java

src/Status.java

src/Student.java

src/UniversityMember.java

src/enumeration/BachelorDegree.java

src/enumeration/BachelorSemester.java

src/enumeration/CourseType.java

src/enumeration/ExamType.java

src/enumeration/FieldOfStudy.java

src/enumeration/Gender.java

src/enumeration/Mark.java