v1.1.3 refactor

[reececomo]

What's changed?

• Reformatted, split into modular files.
• Disable extending Action manually:
  • There's a few easy, well-documented methods to create custom actions already.
  • Actions are stateless, so extending the class manually is not a good way.
• Added a few more tests.

Next steps:

• I think next release will be to disable automatically registering the global mixin registerGlobalMixin(), so the developer can choose when and where.