Stop TracedStatement throwing warnings for objects

[AnthonyPorthouse]

The current behaviour of TracedStatement::checkParameters() will cause warnings to be raised when objects are passed in as a parameter. This should not always be the case.

This PR adds support for both objects with and without __toString() methods.

If an object has a __toString() method, then we will call that and use that as our parameter.

If it does not, then we will short circuit the encoding check and just make it show up as [BINARY DATA].

Another option, which is preferred would be to add another possible value such as [OBJECT classname] which would differentiate it from standard binary data.