Migration, refactoring and code style unification to support latest PyZenKit...

Migration, refactoring and code style unification to support latest PyZenKit and Pynspect libraries.

This huge update represents a lot of work on many parts of the system. After major upgrade in PyZenKit and Pynspect libraries it was necessary to bring this project up to date. There were many changes in the code, lot of refactoring and while all this was done, code quality was improved, documentation written and unit tests modified. Many of these changes simply make sure, that the code works with latest versions of both libraries. This commit is supposed to be a single major feature upgrade, after this only smaller commits will follow to polish this huge amount of work.

(Redmine issues: #3374, #1017, #3361, #3387, #3443)