Improve decorations, custom blending & Add vanilla skyboxes

[FlashyReese]

Refactor Summary

This PR improves the decorations system by enabling each decoration to be rendered separately. Previously, decorations could only be declared in one skybox, meaning that it was impossible to place sun/moon/stars separately.

Illustration of changes (Courtesy of @UsernameGeri)

Motivation

The motivation behind these changes is to provide greater flexibility and customization options for users when designing skyboxes. By allowing decorations to be rendered separately, users will have the ability to place sun, moon, and stars wherever they choose, resulting in more unique and creative skyboxes. This will ultimately enhance the user experience and improve the overall quality of the game.

[FlashyReese]

This latest commit improves the implementation of the blend object specification, especially when defining custom blend modes. As part of this update, we have introduced a new custom blender object that you can now specify within the blend object. The custom blender will only be used if the blend object type property is set to custom. Additionally, this commit includes the addition of new blend mode types - disable and decorations.

[FlashyReese]

Changes

• Improve and moved custom blend mode into blender object.

  "blend": {
  "type": "custom",
  "blender": {
  "separateFunction": true,
  "sourceFactor": 770,
  "destinationFactor": 1,
  "equation": 32774,
  "sourceFactorAlpha": 1,
  "destinationFactorAlpha": 0,
  "redAlphaEnabled": false,
  "greenAlphaEnabled": false,
  "blueAlphaEnabled": false,
  "alphaEnabled": true
  }
  }

• Add support for blend function separate.
• Add overworld and end skybox type.
  • overworld skybox type will render the vanilla overworld sky + sunset/sunrise hue.
• Allow more than 1 decoration to be rendered.
• Add blending for decorations.

  "decorations": {
  "blend": {
  "type": "decorations",
  "blender": {}
  }
  }

• Add decorations and disable blending modes.
  • decorations is the default blending mode for decorations.
  • disable blend mode does as named.
• Fix rotation precision, this resolves #83.