Fixes syntax error in LoadScenery function

- The LoadScenery function wasn’t setting the number of materials
correctly.
Changes step size in shifts

- The shift step size has been increased for left, right, up and down
directions.
Adds drawing of scenery

- Scenery can now be drawn via the DrawScene function.
Adds depth testing to scene renderer

- Depth testing on scene renderer now takes place.
- Perspective has been altered.
- Lighting enabled.
- Depth function adjusted to allow overlapping lines.