RFC: nested output handler issues

Current nested output handler implementation has some problems. Problem: User can accidentally delete zlib output handler. This may lead to SIGPIPE and/or no output after deletion. (Bug#14226) Other internal handler may also be deleted. (mbstring output conversion, trans sid handler, iconv, anything else?) Solution: Make 2 output handler lists for internal(module) and user use. Disallow deleting internal output handlers from script. Side Effect: User may *not* able to turn off output buffering using ob_end_clean()/ob_end_flush(). (ob_implicit_flush() can be used, though) If nobody objects or writes patch, I'll write one. If you have comments, please let me know before I start coding. (I'll wait about a week for feedback at least) Thank you for your comments. -- Yasuo Ohgaki