Revert spontaneous style change.
Properties is now can be assigned via logger service.

* unpacker for logging properties implemented.
* `log_property_map_t` is now called as `properties_t`.
Drop unnecessary method call.
Naming.
Some description added.
Time and level formatters are no longer virtual.

Actually, we don't need dynamic polymorphism here.
Code cleaning up.
Pack traits (temporary, yet) for log properties has been added.

Until magic dynamic class comes.