Add xdebug support for Twig template debugging

It might be very useful add support for debugging twig templates with xdebug.
The idea is stolen from here (AjglBreakpointTwigExtension). The implementation in devel is quite simple and consists in few lines of code. Debugging twig template with xdebug is simple as put

{{ devel_breakpoint() }}

in the template of interest. When the template is evaluated is made a call to devel's twig debug extension in which you use xdebug_break(), that emits a breakpoint to the debug client. In this way you'll be able to inspect any variables available in the template (enviroment, context, specific variables etc..) in your IDE using xdebug.

Edit:
I noticed that a module for this already exists for drupal 8 (twig_xdebug) but it could still be useful to include this functionality in the devel module.