change of + the DateAndTime breaks the tests

when I read testDateTimeDenotation1 it seems correct to me.

Now do you remember why you changed 

DateAndTime>>+ operand
"operand conforms to protocol Duration"

| ticks |
ticks := self ticks + (operand asDuration ticks) .

^ self class basicNew
ticks: ticks
offset: self offset; 
yourself

to be 

DateAndTime>>+ operand
"operand conforms to protocol Duration"

| ticks |
ticks := OrderedCollection new.
self ticks with: (operand asDuration ticks) do: [:ticks1 :dticks |
ticks addLast: (ticks1 + dticks) ].

^ self class basicNew
ticks: ticks asArray
offset: self offset;
yourself.


Thanks

Stef