private void txtLegajo_KeyPress(object sender, KeyPressEventArgs e)
 {
     Validar.SoloNumeros(e);
 }
 private void txtMateriaCarrera_KeyPress(object sender, KeyPressEventArgs e)
 {
     Validar.SoloLetras(e);
 }
 private void txtNombre_KeyPress(object sender, KeyPressEventArgs e)
 {
     Validar.SoloLetras(e);
 }