Add support for a custom header

Signed-off-by: Lars Hjemli <hjemli@gmail.com>
diff --git a/cgit.h b/cgit.h
index 4fe94c6..4942b96 100644
--- a/cgit.h
+++ b/cgit.h
@@ -135,6 +135,7 @@
 	char *css;
 	char *favicon;
 	char *footer;
+	char *header;
 	char *index_header;
 	char *index_info;
 	char *logo;