Allow to create variants of custom objects

[D8H]

Changes

• Custom objects can now have several inner scene tabs called variants.
  • For instance, you can design 2 buttons variants: one green, one yellow and use them across the game. When you change the label font of the yellow button variant, it will apply to every yellow button of the game.
• Variants tabs don’t allow to add or remove objects, behaviors, group or variables. Changes must be done in the custom object inner scene tab that can be opened from the extension editor.
• Assets from the store will be installed as variants. These variants can't be edited to avoid any loss downloading them again, but they can be duplicated to be edited.
• A special property must be used in the extension editor to map text content from properties to child-objects. This will no longer be necessary when the 3D editor is released.

Known issues

• Variants can't be renamed.
• Variable cross renaming will result to instance variable value loss (in general, it's not specific to variants).
• Variants can't be easily moved from one project to another
  • Variants are stored in extensions but they are not exported with the extension.
  • The events-based objects or the extension can be copy-pasted to another project, but resources need to be imported to the other project manually.
  • We could allow to import back GDO to solve this issue.

Demo

• TestVariant.zip

Require

• Allow anchored objects to move #7417