ob-screen: Respect :session name. Don't prepend 'org-babel-session-'

* lisp/ob-screen.el (org-babel-prep-session:screen): Remove concat of
"org-babel-session-" string onto session name when creating session.
(org-babel-screen-session-socketname): Remove concat of
"org-babel-session-" string onto session name searching for existing
screen session.

etc/ORG-NEWS

@@ -380,6 +380,13 @@ From ~org-enable-priority-commands~ to ~org-priority-enable-commands~.
 From ~org-show-priority~ to ~org-priority-show~.
 
 ** Miscellaneous
+*** =ob-screen.el=: Respect screen =:session= name
+
+Screen babel session are now named based on the =:session= header
+argument (defaults to ~default~).
+
+Previously all session names had  ~org-babel-session-~ prepended.
+
 *** Forward/backward paragraph functions in line with the rest of Emacs
 ~org-forward-paragraph~ and ~org-backward-paragraph~, bound to
 ~<C-UP>~ and ~<C-DOWN>~ functions mimic more closely behaviour of

lisp/ob-screen.el

@@ -62,8 +62,7 @@ In case you want to use a different screen than one selected by your $PATH")
          (process-name (concat "org-babel: terminal (" session ")")))
     (apply 'start-process process-name "*Messages*"
            terminal `("-T" ,(concat "org-babel: " session) "-e" ,org-babel-screen-location
-		      "-c" "/dev/null" "-mS" ,(concat "org-babel-session-" session)
-		      ,cmd))
+		      "-c" "/dev/null" "-mS" ,session ,cmd))
     ;; XXX: Is there a better way than the following?
     (while (not (org-babel-screen-session-socketname session))
       ;; wait until screen session is available before returning
@@ -97,8 +96,7 @@ In case you want to use a different screen than one selected by your $PATH")
 			 nil
 			 (mapcar
 			  (lambda (x)
-			    (when (string-match
-				   (concat "org-babel-session-" session) x)
+			    (when (string-match session x)
 			      x))
 			  sockets)))))
     (when match-socket (car (split-string match-socket)))))