add delete-headers to rfc822, that removes a header entry

scheme/lib/rfc822.scm

@@ -200,6 +200,14 @@
 	 (string-join (cadr entry)
 		      (:optional maybe-sep "\n")))))
 
+(define (delete-headers headers name)
+  (fold (lambda (entry rest)
+	  (if (eq? (car entry) name)
+	      rest
+	      (cons entry rest)))
+	'()
+	headers))
+
 
 
 ;;; Other desireable functionality

scheme/packages.scm

@@ -61,6 +61,7 @@
 	  get-header-all
 	  get-header-lines
 	  get-header
+	  delete-headers
 	  ))
 
 (define-interface uri-interface