Clean up.
Proper datetime marker initialization.
Implemented and tested datetime watcher initialization from factory.
Decomposition over datetime watcher’s period factory.
Code style.
Removed unnecessary incapsulation.
Merge branch 'master' of github.com:3Hren/blackhole
Moving `perio_t` class from templated parent class to the separate namespace.
Custom watcher set class implemented.
Some tests has been added.