Inconsistent naming for etcommon-bigint

[pyskell]

To use etcommon-bigint you need to specify it as etcommon-bigint in your Cargo.toml but as bigint in your main.rs.

Example:
Cargo.toml:

[dependencies]
etcommon-bigint = "0.2.9"

main.rs:

extern crate bigint;

I believe this mismatch is due to the following in https://github.com/ETCDEVTeam/etcommon-rs/blob/master/bigint/Cargo.toml#L11:

[lib]
name = "bigint"

I realize changing this now would break dependencies but it is a bit confusing when trying to work with the library so maybe adding a note to the docs would be helpful? If so I can submit a PR next week.

[whilei]

That would be great @pyskell, thanks :)