update the functions

1. text label to display the light information.
2. selected first, then translation or rotation or change intensity.
3. when light attached the beams, the system will automatically drag the
light in the correct position, which avoids the occlusion problem of
light and beams.
4. rotation the lamp of the light, the rotation of the base is constant.

Things I have not done:
1. the collision detection between the lights and the theater.
2. the rotation problem: when the light project to the hall, it is OK,
but when the light projects to the camera, the rotation is opposite.
add new functions and fix the previous bugs