Improve message for deprecation of doubling methods named "method"

[aimeos]

The deprecation warning isn't currently very useful because it doesn't tell which class or interface does implement the method named method. In our case, none of our objects implement that method so we are not sure where it comes from (e.g. a 3rd party package) or if it's related to another issue.

The class name where the method is implemented would be very helpful.

[aimeos]

Thanks a lot!