Selectively enable extensions

I wanted to use the module only for the text (truncate) function of twig_extensions. While it made my life easier on that, I ended up having to debug several things ( #2694185: PHP intl extension missing → , #2726531: Error after upgrading to Drupal 8.1 → ).

I thought of improving the module, so that one could load the extensions he wants from the settings file.

A version that does exactly that is here https://github.com/bserem/twig_extensions
and the diff is here: https://github.com/bserem/twig_extensions/commit/e08089d23ce00d678e84ad8...