Pass instantiated types to type_guess

[edurand]

Hello,

At the moment, type_guess takes a types optional argument that is a list of type classes for data to be checked against.

I think the code would be more flexible if instead it took instances of type objects. Then users could modify the classes a little more easily. e.g. one could change the defaults of BoolType, which I find matching way too many things as is, especially on a sample of the file.

Thanks