[feature request] `from_iter` constructor

[neil-morrison44]

Hi,

I'll probably take a look at this myself, creating an issue first incase you can point out it's impossible or any pitfalls.

What I'm after is a from_iter, similar to from_slice but it'd get given an iter which returns u8s instead of a u8 array. (I'm reading GIF files off of an SD card & the GIFs can be too large for a full one to fit in memory).

It'd pull the headers etc from the input iter, store them same as what happens with the from_slice. I think it it'd need to return frames as an iterator over frame & would only be able to do 1 loop (since the input iter will get consumed), but other than that I'm not seeing any major issues

[abergmeier]

Will try to take a stab at that, too.