Decorators: Better method inheritance handling and logs

- When a callback setup find an error, the complete method description
is given (with name, source file and line) instead of just its name
- The is_from_parent method now accepts an optional value to be tested
in parameter. It ensures that the tested value comes the child class,
not from a parent one.
iPOPO: Log an error if a class is manipulated twice

When a class has two @ComponentFactory decorators, stop at the first
(lowest) one.
An error message is printed in that case.