Add support for callable typehint to reflection

. $method->getParameter($offset)->getTypeRestriction() will yield Type::$CALLABLE
. $method->getParameter($offset)->getType() will yield a FunctionType instance
. The type literal for Type::$CALLABLE is "callable"
. At the same time, centralize native types: Primitive::$ARRAY -> Type::$ARRAY
Merge branch 'master' of github.com:thekid/core