New /clearcache route; javascript block moved in head

	modified:   resources/views/layout.html.twig
	modified:   src/controllers.php

	The javascript code to eval can now use the jquery.
initial refactoring of the code eval handling

    $interp is now called $lang
    the routes have the same name as $lang
    added a clearcache route and method
    moved code related handler to CodeController.php