Emerald OS Round 2

Credits: 

@ttt1101 : for managing the team, making most of the costumes, and making the draw_box function.

@creeperdoesredstone : for helping with the text engine, a wallpaper, along with other things.

@matthewjaynichol : for designing concepts for the UI, and a wallpaper.

@PhatCV : for making a wallpaper.

Me, for most of the graphics engine (rectangle engine, text engine), the input engine (mouse and keyboard), and most of the OOBE code.

The rest of the Emerald OS team.

@Chrome_Cat for inspiration for the rectangle filling algorithm.