Remove arguments from 'webpaste-paste-buffer-or-region'

Since (interactive "r") fails when starting Emacs (or creating new buffers,
perhaps?) with the following error message:

  execute-extended-command: The mark is not set now, so there is no region

Since this commit changes the function arguments, it might break some existing
calls from Elisp, and this might not be worth it.

webpaste.el

@@ -618,15 +618,14 @@ Argument MARK Current mark."
 
 
 ;;;###autoload
-(cl-defun webpaste-paste-buffer-or-region (&optional point mark)
-  "Paste current buffer or selected region to some paste service.
-Takes optional POINT and MARK to paste a region."
-  (interactive "r")
+(cl-defun webpaste-paste-buffer-or-region ()
+  "Paste current buffer or selected region to some paste service."
+  (interactive)
 
   ;; if region is selected
   (if (region-active-p)
       ;; Paste selected region
-      (webpaste-paste-region point mark)
+      (webpaste-paste-region (region-beginning) (region-end))
     ;; Else, Paste buffer
     (webpaste-paste-buffer)))