Symfony 4, Twig 3 and FosMessage 2

[vhrychenko]

Hi.
I've upgraded my Symfony project from 3 to 4 and I faced an issue with MessageExtension class.

`In MessageExtension.php line 12:

Attempted to load class "Twig_Extension" from the global namespace.
Did you forget a "use" statement?
`

so the problem that Twig_Extension is not compatible with Twig 3, it works only for Twig 2. What I do is rewriting directly in vendor folder the code to TwigExtension base class and it works. The same for Twig_Function at lines 35-38.

How can I override it on the project level or can you push the fix as a new patch?

[hex333ham]

see here for info on updates - #351