Support implicit reset

[dogtopus]

I am reversing a proprietary image format that uses LZW internally for compressing frames and I also plan to write a converter for it in Rust as a practice. I chose weezl because it looks promising and it's already a dependency for image-rs which I am also using in the converter for reading/writing images in common formats.

However one problem that I ran into is that weezl doesn't like bitstreams with no leading clear code. The official converter for that image format apparently always emits such type of bitstreams. Other than that they just seem to be standard LZW LSB bitstreams and should be supported by weezl. I saw that there's a TODO in the decoder source code. Any chance that this will be supported?

[HeroicKatora]

There is no particular plan for it but PRs are always welcome. This also seems like a sufficiently local change for first contributions, though there might be some finesse involved in the interface. Guidance and reviews are also available upon request.