unwrap()s expect()s and other panic!("the disco")

[gshipunov]

This is a library. Anything that can lead to panic should only be acceptable due to a bug. Any errors needs to be either handled or propagated to the caller, so the service using the library can decide if it needs to panic in this situation by itself.

Should be an easy fix, just grep for any unwrap()y code, and write some custom error enums.