Provide human-readable error chain description & error grouping APIs

[Jeehut]

Fixes #17.

Note that I found a much simpler solution than what was outlined in the issue, which would have required a lot more work on our end (writing a Mac app) and also on the users end (setting up everything). This solution is much more practical and can be picked up by developers much more quickly. It's also less intrusive.

[n0rthk1n9]

Not having the chance of errors is bothering me a lot in my own code, I like it! After changing the German error message example to an English one, you can merge this.