fix some c&p bugs.
sync function signatures with tzcode
Sync with tzcode2014h
mention new tzcode.
set some variables we need
remove version stuff
add defines
Fix backslashes
don't define functions we define in our own headers
Some years don't need the "maybe add 1900 or 2000" adjustment
that was designed for handling two-digit abbreviated years.
For example, "1/2/70" still refers to the year 1970, as before,
but "70-01-02" now refers to the year 70.

* Add a new yyHaveFullYear member to struct dateinfo, to record whether
  or not the year needs to be adjusted.
* Code that parses years sets yyHaveFullYear=1 if they know that the
  year should not be adjusted (as is the case for ISO 8601 dates), or if
  they perform their own adjustment (as is the case for CVS timestamps).
* Move the year adjustment code into a new function, AdjustYear,
  instead of inline in Convert().
* Make Convert() assume the year doesn't need to be adjusted,
  and make Convert's callers first call AdjustYear() if appropriate.
Adapt to a recent change in parsedate().
"9/10/69" still refers to 2069, and "9/10/70" still refers to 1970,
but "69-09-10" and "70-09-10" now refer to the years 69 and 70.
Document that years in ISO 8601 dates are taken literally.
"69-09-10" is in the year 69, not 2069.