[*][DEV]: add new interface calculateDays() in TimeSpanUtils to
calculate days between two dates except weekdays defined in filter;
[*][DEV]: update unit test for TimeSpanUtils to test calculateDays();
[*][DEV]: add new interface calculateOverlapDuration() in TimeSpanUtils
to calculate duration in millis between two time spans;
[*][DEV]: update unit test for TimeSpanUtils to test
calculateOverlapDuration();
[*][DEV]: add plus method for ExpressToken and Column;
[*][DEV]: add minus/multiple/divide/modulo method for ExpressToken and
Column;
[*][DEV]: fix a bug in calculateOverlapDuration();
[*][DEV]: add eq/neq/lt/lte/gt/gte of ExpressionToken;