[tz] [PROPOSED] Rename internal identifiers to match RFC 8536

[Stephen Colebourne]

On Sun, 16 Jun 2019 at 20:14, Paul Eggert <eggert at cs.ucla.edu> wrote:
> Going forward it’s better
> to stick with the RFC terminology in internal identifiers.  This
> change does not affect longstanding and standard APIs

> @@ -89,7 +89,7 @@ Rule  Algeria 1980    only    -       Apr     25       0:00   1:00    S
>  Rule   Algeria 1980    only    -       Oct     31       2:00   0       -
>  # Shanks & Pottenger give 0:09:20 for Paris Mean Time; go with Howse's
>  # more precise 0:09:21.
> -# Zone NAME            GMTOFF  RULES   FORMAT  [UNTIL]
> +# Zone NAME            UTOFF   RULES   FORMAT  [UNTIL]

This is clearly a change to the API as seen by downstream consumers.
Some downstream consumers may well parse the file and look for a
column named "GMTOFF".

As it happens, Joda-Time and ThreeTen-Backport do not parse the column
name. But, given the quantity of downstream consumers of those files,
I'd imagine at least one does.

This change should be reverted, as it is unnecessary and may well
cause downstream pain.

Stephen