Faster way to dispatch on type of Py object?

[jverzani]

As of #19, in asSymbolic there is dispatch on asSymbolic(Val(typename(x)),x). The creation of a type to dispatch on from x seems much slower than it should be. It basically creates a string from the _module__ and __name__ parts and then a Symbol and then a type. I don't think there is a way to go from x to a Symbol, but putting this here incase something seems possible