Fix bugs and make improvements

- Fix regression with `%lu`
- Added some more headers witnessed in the wild
- Added `-M INT` option to redbean to tune max payload size
- Work around InfoZIP 256 character limit on comment line size

net/http/khttprepeatable.c

@@ -78,4 +78,8 @@ const bool kHttpRepeatable[kHttpHeadersMax] = {
     [kHttpVia] = true,
     [kHttpWarning] = true,
     [kHttpWwwAuthenticate] = true,
+    [kHttpAccessControlAllowHeaders] = true,
+    [kHttpAccessControlAllowMethods] = true,
+    [kHttpAccessControlRequestHeaders] = true,
+    [kHttpAccessControlRequestMethods] = true,
 };