Update to iOS17 and fixed known issues.

Support dark mode.

Eraser now available.

More fun with five new drawing patterns: grid and 4 parallel patterns.

1) New drawing mode with mirror effect and more.
2) Add a pointer tool which can help drawing more precisely.

Now you can save your art and edit it in the later.
1）Touch Camera icon to save the art.
2)  Touch Book icon to manage saved arts.

Optimize UI for iOS11 & iPhone X.