[tz] zdump new option -i for easier-to-review output

[Paul Eggert]

Jon Skeet wrote:

> it isn't canonical at that point - from the perspective of
> information in the source text. If two valid implementations can give two
> different outputs, that's a problem for my use case.

We have that problem anyway. If zdump is run on a platform with 32-bit or 
unsigned time_t, it will generate different output from platforms with 64-bit 
signed time_t. This is true even when using the tzcode localtime.c implementation.

I plan to generate the reference file on a host with 64-bit signed time_t and to 
use the reference tzcode implementation. So long as you test on a similar 
platform we should be OK.

> if the output data in the
> release will always use 1 and 0, I guess I could canonicalize to that

Yes, it should always be 1 or absent.