Swank dosen't have key "coding-system". 

Swank dosen't have key "coding-system". Have to try another way to avoid character set encoding error, here is the code only for SBCL:
```
;;; To prevent charset encoding error.
(defun set-default-external-format (external-format)
  "Usage: (set-default-external-format '(:UTF-8 :REPLACEMENT #\REPLACEMENT_CHARACTER))"
  (assert (sb-impl::find-external-format external-format))
  (setf sb-impl::*default-external-format* external-format)
  (setf sb-alien::*default-c-string-external-format* external-format)
  (with-output-to-string (*error-output*)
    (setf sb-sys:*stdin*
          (sb-sys:make-fd-stream 0 :name "standard input" :input t :buffering :line))
    (setf sb-sys:*stdout*
          (sb-sys:make-fd-stream 1 :name "standard output" :output t :buffering :line))
    (setf sb-sys:*stderr*
          (sb-sys:make-fd-stream 2 :name "standard error" :output t :buffering :line))
    (setf sb-sys:*tty* (make-two-way-stream sb-sys:*stdin* sb-sys:*stdout*))
    (princ (get-output-stream-string *error-output*) sb-sys:*stderr*))
  (values))
(set-default-external-format :utf-8)
```

ssh is better to run in the background. So the better command is:
```
ssh -N -f -L 4005:127.0.0.1:4005 username@remote.example.com
```
NOTE:
    -N to tell ssh "this is only for port redirect, not for more command"
    -f to tell ssh "run in the background"
Merge pull request #3 from muyinliu/patch-1

Swank dosen't have key "coding-system".