Add a method to get the timestamp's string representation using a custom date format.
Add a method to get the timestamp's string representation using a custom date format.

openxal/openxal,luxiaohan/openxal-csns-luxh,openxal/openxal,EuropeanSpallationSource/openxal,openxal/openxal,openxal/openxal,EuropeanSpallationSource/openxal,EuropeanSpallationSource/openxal,luxiaohan/openxal-csns-luxh,luxiaohan/openxal-csns-luxh,openxal/openxal,luxiaohan/openxal-csns-luxh,EuropeanSpallationSource/openxal,EuropeanSpallationSource/openxal