Remove ChainedError trait

[brson]

It's presently not serving much purpose.

[ahmedcharles]

I've looked at this. What's the plan for the functionality contained in the trait? I.e. what does the removal look like at a high level?

[Yamakaky]

That would mean moving the code in the macro.

[ahmedcharles]

It turns out that implementing DisplayChain requires accessing the backtrace and there's no way to do that without a trait of some form. The only other solution would be moving code from src/lib.rs into the macro, which just seems like it would cause additional bloat.

[kohensu]

Hi, I did a pull request (#244) that address this issue, is there some one to review it ?

[Ottawan]

I'm using ChainedError as associated type for trait. What would be my alternative if/when it's gone?