Undo/redo behavior and multiple selection fixes

This update addresses issues with undo/redo functionality and improves the selection of multiple objects.

Changes

• Fixed issue undo/redo not behaving as expected.
• Fixed issue error that sometimes occurred when selecting multiple objects.
• Fixed missing shadows issue when loading a file that should have them.
• Fixed issues when exporting big images.
• Fixed issues when using the frame.
• New: You can now subdivide cones and pyramids.
• New: Performance improvements.
• New: Added Rainbow Iridescence layer.
• New: Added UV Projection Mapping to Texture layer.
• New: Added dithering to all materials, no more color banding!