BUGS:

- fix backtraces
- exit in PHP exits Roxen
- POST newline added?
- Rewriting header handling so that more than one header with the same
  name can be set (most importantly, cookies).
- Recursive mutex lock problem:

    And another error (when trying to include a class)
    
    Recursive mutex locks!
    /Usr/local/pike/7.0.54/lib/modules/PHP4.so.Interpreter:
    run("/home/www/www.tx.pl/news/test.php",mapping[3],modules/scripting/php4.pike.PHPScript(),modules/scripting/php4.pike.PHPScript.done)
    modules/scripting/php4.pike:169: run()
    base_server/roxen.pike:569: handler_thread(3).
    
    And after this every access to any php script (on other virtual sites
    also) ends (of course there is no proper output) with this error:
    
    Php4.Interpreter->run: Tried to run a PHP-script from a PHP
    callback!/usr/local/pike/7.0.54/lib/modules/PHP4.so.Interpreter:
    run("/home/www/biall.com.pl/index.php3",mapping[2],modules/scripting/php4.pike.PHPScript(),modules/scripting/php4.pike.PHPScript.done)
    modules/scripting/php4.pike:169: run()
    base_server/roxen.pike:569: handler_thread(3).
    

ADDITIONS:

- use th_farm
- change cwd in single threaded mode
- per-virtual-server configuration

