Implement Hash, PartialOrd, Eq, Ord for types

[PonasKovas]

Hello, it would be awesome if the Nbt types could implement these traits, if possible.

And also, quick unrelated question - can the nbt writing methods ever fail with any error other than IO? maybe they should return Result<..., io::Error> instead of crab_nbt::Error?

[goteusz-maszyk]

Well, hashmaps niether do support hashing nor ordering. We cannot also implement Eq because of floats.

[SzczurekYT]

Poor research, not all of them, but some of the traits can be actually implemented.

[SzczurekYT]

Alright
I thought more of the traits are actually missing then they are.
Sorry for calling you out @goteusz-maszyk
Your research was generally correct, but a bit inaccurately described in the comment.
This led @Norbiros to make this comment on #18

Maybe switch to Vec<String, NbtTag> instead of Hashmap to preserver order, and resolve #22

which made me a little upset.

The actual situation is as follows:

• Hash, Eq, Ord can't be implemented in any way because nbt can store floats, which do not implement those traits. So putting stuff into a Vec instead of HashMap as @Norbiros suggested is not going to solve this issue in any way, and only going to cause more problems.
• PartialOrd can be actually implemented and it is tracked here Implement PartialOrd for nbt types #23

[SzczurekYT]

TLDR: PartialOrd has been implemented and other traits can't be implemented because of floats