More doc comments
Converts NanoError to IoError in Reader and Writer trait implementations
Improves NanoError to IoError conversion
Improves NanoError to IoError conversion
Adds doc comment to drop function
Adds a Req/Rep example
Adds back FromError trait implementation for NanoError

FromError trait is required to work with the try! macro
 - Adds back previously removed impl
 - Adds a test tp ensure the impl won't be removed again
Improves from_err conversion

 - Use the io err description in the nano err
 - Performs some basic kind conversion
Merge pull request #86 from blabaere/master

More doc comments