This is a collection of miscellaneous timezone manipulation routines.
tz2zone() parses the TZ environment variable and returns a timezone
string suitable for inclusion in date-like output. It opionally takes
a timezone string, a time, and a is-dst flag.
tz_local_offset() determins the offset from GMT time in seconds. It
only does the calculation once.
tz_offset() determines the offset from GMT in seconds of a specified
tz_name() determines the name of the timezone based on its offset