Add supply teachers to departments

orm/department.go

@@ -25,7 +25,7 @@ var (
 	selectUniqueDepartmentTeachers = `
 SELECT DISTINCT teachers.* FROM subjects 
 INNER JOIN activities ON activities.subject_id=subjects.id 
-INNER JOIN teachers ON activities.teacher_id=teachers.id 
+INNER JOIN teachers ON (activities.teacher_id=teachers.id OR teachers.id=activities.supply_teacher_id)
 WHERE department_id=?`
 
 	selectUniqueDepartmentSubjects = `