babel: shell: New variable assignment and expansion scheme

	* ob-sh.el (org-babel-execute:sh): Use generic expansion
	function
	(org-babel-expand-body:sh): Delete function
	(org-babel-prep-session:sh): Change name of called function
	(org-babel-variable-assignments:sh): Change function name

lisp/ob-sh.el

@@ -45,19 +45,14 @@
   "Command used to invoke a shell.
 This will be passed to  `shell-command-on-region'")
 
-(defun org-babel-expand-body:sh (body params)
-  "Expand BODY according to PARAMS, return the expanded body."
-  (mapconcat #'identity
-	     (append (org-babel-sh-variable-assignments params) (list body))
-	     "\n"))
-
 (defun org-babel-execute:sh (body params)
   "Execute a block of Shell commands with Babel.
 This function is called by `org-babel-execute-src-block'."
   (let* ((processed-params (org-babel-process-params params))
          (session (org-babel-sh-initiate-session (nth 0 processed-params)))
          (result-params (nth 2 processed-params)) 
-         (full-body (org-babel-expand-body:sh body params)))
+         (full-body (org-babel-expand-body:generic
+		     body params (org-babel-variable-assignments:sh params))))
     (org-babel-reassemble-table
      (org-babel-sh-evaluate session full-body result-params)
      (org-babel-pick-name
@@ -68,7 +63,7 @@ This function is called by `org-babel-execute-src-block'."
 (defun org-babel-prep-session:sh (session params)
   "Prepare SESSION according to the header arguments specified in PARAMS."
   (let* ((session (org-babel-sh-initiate-session session))
-	 (var-lines (org-babel-sh-variable-assignments params)))
+	 (var-lines (org-babel-variable-assignments:sh params)))
     (org-babel-comint-in-buffer session
       (mapc (lambda (var)
               (insert var) (comint-send-input nil t)
@@ -86,7 +81,7 @@ This function is called by `org-babel-execute-src-block'."
 
 ;; helper functions
 
-(defun org-babel-sh-variable-assignments (params)
+(defun org-babel-variable-assignments:sh (params)
   "Return list of shell statements assigning the block's variables"
   (let ((sep (cdr (assoc :separator params))))
     (mapcar