extending the time range

[Chris Torek]

All of the proposals I have seen have `RETROFIT' stamped upon them
in garish glowing ink.  None seem very pretty.  Instead of a
retrofit, it seems to me one should define a new type, at least 64
bits wide, measured perhaps in microseconds.  localtime &c should
be renamed, and changed work on these new time values; compability
routines would transform old `time_t's to new values, and then
return the value returned by the new routines.

Chris