Remove duplicated info in some debug messages

[Vulcalien]

In the code, we can find code like this:

dbg('ConfigBase::get_item: %s found in globals: %s' %
                    (key, self.global_config[key]))

But this gets printed:

ConfigBase::get_item: ConfigBase::get_item: focus found in globals: click

There is a repetition, because the dbg function already adds the name of the function at the beginning (4d21663).
The same should probably have been done to the err function.

This change should make the debug logs easier to read.

[mattrose]

Thanks for this, this is something that was an irritant to me up until now.