Fix reading of entire email, not just headers

Apparently mel:message-header-stream gives you a stream that can access
the whole email.

mailfilter-parse.lisp

@@ -126,6 +126,9 @@
       (loop-file-until s (lambda (x) (declare (ignore x)))  #'parse-line hash))
     hash))
 
+(defun end-of-headers-p (line)
+  (= (length line) 0))
+
 (defun message-match (message pattern)
   (let* ((scanner (cadr (gethash "regex" pattern)))
          (regex (car (gethash "regex" pattern)))
@@ -133,7 +136,7 @@
          (test))
     (with-open-stream (message-stream (mel:message-header-stream message))
       (loop for line = (read-line message-stream nil)
-            while (and line (not test))
+            while (and line (not test) (not (end-of-headers-p line)))
             do
                (setf test (cl-ppcre:scan scanner line))))
     test))