Lithophane update

1. In the previous lithophane functions, the base, lamp socket, and lithophane were generated as disconnected components. In this update, all components are generated as one body.

2. Flat and Arc lithophane have socket types: O and U.

3. Rectangle, Hexagon, Octagon, and Dodecagon lithophane have a control over base thickness.

4. Cylinder, Cone, and Vase lithophane have a solid vs. hollow base option. If using a hollow base, a lamp socket can be generated.