Refactor some code

[daisuke201]

Background

The current implementation of the mapray JS includes code that can be improved in terms of readability, maintainability, and performance.

[daisuke201]

Specifically, the following components could benefit from refactoring:

• ImageProvider
• DemProvider
• Program.js
• Globe
• Material
• Mesh

Refactoring these components will improve the overall quality of the codebase, making it easier to understand, modify, and maintain.

[daisuke201]

Have refactored some codes in v0.9.1