Add the ability to consume the IconImage

[StratusFearMe21]

This is useful for embedding an ico window icon and using it with winit, which requires that the icon is a Vec<u8>

[mdsteele]

Thanks, this looks like a good method to add.

[mdsteele]

Looking at standard library methods, it seems like the usual Rust convention is for "take" to refer to &mut self methods that extract an owned value, leaving (that part of) the receiver object empty (e.g. slice::take_last), while self methods that consume the receiver entirely to return an owned value have names starting with "into" (e.g. Box::into_raw). So by that convention, this method should probably be called into_rgba_data instead.

[StratusFearMe21]

Yeah, you're right. Updated

[mdsteele]

Looks good, thanks, just need to fix the lint error I think? (Looks like just need to run cargo fmt.)