[tz] Proposal: validation text file with releases

[Paul Eggert]

One way forward here would be to give zdump more options to let the user 
specify the format. That way, everybody could use their own favorite 
format. One format might look something like this for 
America/Los_Angeles, assuming the default zdump window of -500 through 
2499 CE UTC:

     -501-12-31 16:07:02 -07:52:58 0 LMT
     1883-11-18 12:00 -08 0 PST
     1918-03-31 03:00 -07 1 PDT
     1918-10-27 01:00 -08 0 PST
     ...
     2016-03-13 03:00 -07 1 PDT
     2016-11-06 01:00 -08 0 PST
     ...
     2499-03-08 03:00 -07 1 PDT
     2499-11-01 01:00 -08 0 PST

(The "1" and "0" are whether DST is in effect.) This completely 
characterizes the data and is more compact and easier to read than what 
zdump outputs now. Other formats might be preferable for other reasons.

It might also be nice to output "PST8PDT,M3.2.0,M11.1.0" at the end, 
instead of that repetitive list of lines starting with the year 2007.