Work to add UTC tracking to wall-times

 * We handle timezones by converting to UTC time during parse
 * Ends up leaving wall-times that look like locatimes,
   but are UTC
 * Causes times to advance by zone-offset every read/write
   to a timezone aware database (postgresql-socket3)
 * To prevent this we will track whether a date will be in UTC
   or is a local time.  When writing out UTC timestamps we add a Z to
   the end
 * During comparison, we always convert to UTC to compare,
   we assume zoneless timestamps are localtimes

There was a lot of personal debate about how to do this. I think a
better answer would be to fully replace clsql-date/times with the
local-time library which has a more comprehensive handling of dates
and times.

re ADWolf:#1408