CURR11 — Add interfaces to DTime properly handle the DAmountOfTime difference inter

Summary: DAmountOfTime difference(in DTime anotherTime) does not support an
implementation properly as the difference between two points in time is a
DamountOfTime instance and DamountOfTime represents an “absolute (positive)
amount of time”. Thus, either DamountOfTime must be able to represent an
amount of time that is less than zero, or the following interfaces must be
available.
· Propose the following additional interfaces:
boolean equal(in CBO::Dtime otherObject);
void setEqual(in CBO::Dtime otherObject);
boolean less(in CBO::Dtime otherObject);
boolean lessEqual(in CBO::Dtime otherObject);
boolean greater(in CBO::Dtime otherObject);
boolean greaterEqual(in CBO::Dtime otherObject);