setDisplayZone  -   sets the seconds d_displayZoneShift wrt UTC.
                    Argument must allow for TZ and DST shifts.

utcSec2timeStruct - receives a *TimeStruct and a time in UTC
                    sets the TimeStruct's tm_isdst flag if the current
                    object's d_dstShift is unequal to zero.

dstCorrection   - returns 3600 if the current time has DST, based on the
                    computer's locattime computation given UTC sec.
                    returns 0 otherwise.

updateTime      - called when a time field (day, seconds, year, fields, etc)
                    is updated. Sanitizes the fields (day 32 -> next month,
                    etc) 

d_tm2d_tm       - receives (TZ + DST) shift in minutes,

d_tm2utcsec     - assigns UTC seconds matching d_tm to d_utcSec

zoneShiftSeconds    - receives zone shift in minutes, returns shift in
                      seconds, based on TZ shifts being multiples of 
                      30 minutes.

