Improvement of HourCounter to synchronize with simulator ClockTime

[li-haobin]

Currently, HourCounter has two ways for recording the count, i.e., ObserveCount(...) and ObserveChange(...), both required ClockTime as the parameter.
However, in O2DESNet v3 the HourCounter is already bound to the Sandbox by AddHourCounter(). Therefore, the ClockTime shall be able to be accessed implicitly instead of explicitly passed in which may cause inconsistency.

In addition, the AverageCount and probably other statistics are updated on the LastTime which is inaccurate, especially in an hourly or short period statistics. Therefore, we shall update the statistics based on ClockTime, which can also 1be handled implicitly.