Allow dynamically created types in Array, etc.

Sometimes, it is nice to be able to create BinData records dynamically. This works wonderfully, except when passing the newly created types to BinData::Array and friends, because they do not show up in the type registry. This allows us to pass a reference to the class in instead of the type reference, bypassing the label lookup (note that the first check might be redundant, I am not too familiar with ===).  

E.g. BinData::Array.new( :type=> @factory.sym, :initial_length => 10).read(@data).snapshot when you have a factory for bindata types...