Security: formatUnixTime and formatUnixTimeGMT read beyond a
heap buffer when the output exceeded 80 bytes. Now the buffer grows.
Security: concurrent calls of the GMT functions could leave the
process-global TZ corrupted. Calls are now serialized and the old
TZ value is copied before being restored.
Windows: fix a heap overflow in _patch_unsetenv, which also failed
to unset TZ.
v0.5.0
Remove deprecated old-time dependency by dropping fromClockTime and toClockTime#68
