Add Debug 'Barrel' and Sandbox class

[patschreiber]

Debug barrel should export all existing modules so a def can easily load in whatever they need.
Sandbox class should be a class that can be optionally loaded to test out functionality.

[patschreiber]

Thinking

+engine
  +development
    -index.ts //barrel for all exported modules
    -sandbox.ts //contains the Sandbox class and loads the barrel