Return early from Renderering if we can't render. Use cloned view man…

…ager helper.

Updated Twig version.

Updates for new TwigRenderer.

Fixes ZF-Commons#60 and ZF-Commons#61.

Properly using TreeRendererInterface instead of the ViewModel injecti…

…on hack.

Added magic __call method to proxy to plugin().

Merge pull request ZF-Commons#51 from Danizord/master

Update to Twig 1.12

Fixed broken plugin helper calls.

Removed unused files.

Merge pull request ZF-Commons#29 from Rovak/cleanup

Cleanup