note 13894 added to function.header.php

For vrml (.wrl for example) made by php, seems obvious to put Header("Content-type: model/vrml"); but for bxx files (blaxxun contact plugin) made by php, don't forget to put it for not being read as text files AND to put something like myscript.php4?bin=.bxx as addy for the file to be read as a chatroom description, not a vrml world (which would of course make an error in the console). (you could change the files types on your server and make that all .bxx files are executed as php scripts and save your bxx generators scripts as .bxx directly thought, didn't look yet in that direction) http://www.php.net/manual/fr/function.header.php