Make chainloader shared
Make chainloader shared

So loaders can be more easily added.
Also used bindIf with $shared=true on the twig itself, which does the
same but more clean. Fixes #123

markhuot/TwigBridge,gencer/TwigBridge,rpouls/TwigBridge,1e4/TwigBridge,diyphpdeveloper/TwigBridge,rcrowe/TwigBridge,gencer/TwigBridge-Laravel-4,jordanlev/TwigBridge