Mouf now disables Composer extensions internally

This fixes issues where buggy extensions causes Mouf to fail.

Fixing bugs in instance using PHP code containing __DIR__ magic constant.

Merge pull request #113 from josealbea/2.0

Fix return_type_from_code.php (error with __DIR__)

Fixing minor bugs on null types management

• in loop detection
• in type annotations containing "null" type

Updating dependencies and moving .composer cache out of vendor/mouf/mouf directory

From this version, the vendor/mouf/mouf directory does not need to be writable by Apache anymore.

Adds a validator on constructor argument loops

If there is a loop in constructor arguments, a validator will now notify you of the problem.

Thank you Mouf! :)