Support for interlace image

There is an image that can not currently be decoded:

fast-png/src/__tests__/decode.test.ts

Lines 22 to 26 in 11a5737

    
           it('interlaced', () => { 
        
             expect(() => loadAndDecode('interlaced.png')).toThrow( 
        
               'Interlace method 1 not supported', 
        
             ); 
        
           });

How difficult is it to enhance the library to support this format ?

I added another smaller image created with Photoshop. It's probably not too difficult to add support for the format but it requires careful reading of the spec and some refactoring to avoid repetition in the code.

Any update about this? Would be really good to be able to handle this files.

+1

	it('interlaced', () => {
	expect(() => loadAndDecode('interlaced.png')).toThrow(
	'Interlace method 1 not supported',
	);
	});