private void button_Login_Click(object sender, EventArgs e)
        {
            string email  = this.textBox_email.Text;
            string parola = this.textBox_parola.Text;

            if (util.userExists(email, parola))
            {
                GLOBAL.idGLOBAL = util.userid(email, parola);
                this.Hide();
                eLearning1918_Elev frm = new eLearning1918_Elev();
                frm.ShowDialog();
                this.Close();
            }
            else
            {
                this.textBox_email.ResetText();
                this.textBox_parola.ResetText();
                MessageBox.Show("Eroare Autentificare");
            }
        }