Accommodate recent Squeak changes for date instantiation relative to UTC versus local time zone.
In Squeak trunk after 3.4 (thus Squeak 4.4) a change has been introduced to TimeSpan such that instances of Date are by default created relative to UTC. This simplifies date comparison, especially for dates that are stored in databases and that are are intended to be comparable independent of the time zones in which they were instantiated. However, a side effect of this change is that date conversion to and from seconds is more complicated because:
dt := DateAndTime now asDate.
dt2 := Date fromSeconds: dt asSeconds.
dt asString = dt2 asString == true
dt = dt2 == false
DateAndTime now offset == -0:05:00:00
dt start offset == -0:05:00:00
dt2 start offset == 0:00:00:00
Therefore add DateasDateInTimeZone: to convert a date with arbitrary time zone offset to a date with start offset for a time zone. Change PointInTime classdate:time:timeZone: to use asDateInTimeZone: to handle dates possibly coerced to UTC. Update tests to accomodate Date instances coerced to UTC. Assume that the start offset of a date is unreliable, and test only that the printString can be compared equal.