tests: fixes
added missing files
Nette\Diagnostics renamed to Tracy (devised by Jan Brbla Bazant)
removed PHP < 5.3 stuff
removed deprecated stuff
removed some Nette dependencies (Nette\Object, Nette\Strings, Nette\Utils\Html, exceptions)
added loader tracy.php
Debugger::isHtmlMode returns TRUE if header Content-Type is not set