Datatype support: unsignedInt

[Ignazio Palmisano]

Some datatypes still not supported:

http://stackoverflow.com/questions/39208460/what-are-datatypes-supported-by-fact/

It's possible to provide basic support leveraging the existing framework (we'll miss some corner cases using just ints for unsigned ints, but it will already improve on the existing functionality). I'll try writing a patch set for this.