Do not trim first characters of messages in error replies.

In the past Redis returned only "-ERR" for any kind of error occurred
on the server using the error reply type, so the "ERR" prefix seemed
kind of superfluous. With recent versions, Redis started using this
prefix to indicate the actual kind of error (e.g. operations on wrong
types return "-WRONGTYPE").
Fix bogus handling of error replies.

Error replies returned by Redis were erroneusly triggering the automatic
reconnection of the client thus leading to infinite loops.

An automatic reconnection mechanism probably sounds nice at first but can
easily lead to unexpected behaviours, and considered that we don't support
them in the binary-safe variants of the commands function it's better to
drop this feature altogether.

This commit fixes issue #12.
Fix segmentation fault due to silly error.