Markdown.pl: process all file arguments

The Markdown function can be called repeatedly, so
stop ignoring file arguments after the first one and
process them all just like the docs claim.

Signed-off-by: Kyle J. McKay <mackyle@gmail.com>

Markdown.pl

@@ -248,12 +248,16 @@ elsif (!caller) {
 
 
 	#### Process incoming text: ###########################
-	my $text;
+	for (;;) {
+	    local $_;
 	    {
 		local $/; # Slurp the whole file
-	    $text = <>;
+		$_ = <>;
 	    }
-	print Markdown($text, \%options);
+	    defined($_) or last;
+	    print Markdown($_, \%options);
+	}
+	exit 0;
     }
 }