Enable antialiasing option for move tool

[khoidauminh]

Gives an option for the artist to transform without smoothing. Useful for pixel art.

[MrStevns]

Hi khoidauminh

Thanks for contributing and sorry for the slow review time.

The PR looks good to me.

It's a bit annoying that we can't see the drawing being affected by the anti-aliasing flag in real time but that's not your fault. It comes down to the way the transformed selection is painted on the canvas which right now requires more involving changes to fix properly.

I have a PR in the works to address that specifically as well as some other concerns regarding the move and selection logic, so for now we'll accept this as a known issue that will be addressed in the future.