- Updated the import dialog to allow users to specify the number of frames in the image (which defaults to 1 x and 1 y)
- Setting the frame count for x and y will draw a dotted line in the preview that shows where the image will be split into individual frames
- When imported with a frame count above 1, the source image will be split into the different frames and loaded just as if it were an animated gif
- This allows users to import existing spritesheet pngs, including those produced by the piskel export function
