Sprite_Editor: A canvas project

A small JavaFX based canvas project which can load picture, and doing various drawing operations Functions of canvas:

1. Canvas Height and Width settinng
2. Random drawing
3. Eraser: Clean previous drawing
4. Show & Hide: show and hide grid reference, each grid represents a pixel.
5. File (on the top left): Can load PNG files to edit, also can save drawings to PNG files.
6. Filling: Filling certain region with the same color.