Version 0.6

- Update the style of the methods following Apple's convention:
https://tinyurl.com/n8jtvj3
- Remove the label from the intro layer there is already project name
in the background logo
- Rename GameBoardLayer to GameLayer
- Rename Slots to Slot
- Update variables in GameLayer to make them more intuitive.
- Fix some grammar and spelling mistakes all over the project
- Move files around to correct folders