- Use the frame signal instead of settimer() with interval 0 to get more
consistent behaviour.
- Update the envmap more often when time warp is active.
- Use maketimer() instead of settimer().
- Terrain and clouds and now rendered on the envmap, with correct aerial
perspective.
- Each face is rendered on a separate frame to help with performance.
- All faces are updated every 1.5 minutes. This can be changed through a
property.
