Fixed typo
added InvalidTemplateDirectoryException Exception
Added twig, defined twig loaders
Auto find & loads Extensions stored in extensions directory
Fixed PHPDoc
Updated construct() and render() methods
Updated
Fixed typo & wording
Set twig.cache_templates to false
Added isTemplateCacheDirectoryValid() method
Merge pull request #8 from maclovr/develop

Add twig, create extensions loader, fix PHPdoc, ...