Refactor TwrObjectPlus subclasses

Remove explicit calls to callbacks. There
is not need expose them, since they are
internals of TwrObjectPlus.
Unify coding style bits

Probably I am exagerating.
Instance checking and refactor TwrObjectPlus

Check that info is an instance of dict in all
cases.

Refactor errors check and my own hacks
outside of the callback itself.
Replace print for logging

Use logging instead of print for libraries.
Release 0.4.0