proposal: add command to create delta-packs in mixer tool about mixer-tools

[phmccarty]

I don't really like the --back option name anymore since it does not describe the option meaning clearly.

--num-versions seems okay, but if you don't mind the verbosity, --previous-versions or --previous-version-count would be more clear to me.

[kevincwells]

+1 I think --previous-versions is pretty good! Probably can infer the "count" from the fact it's an integer.

[matthewrsj]

What does the combination of --back K and --to N produce? Is it K back from N or K back from current and up to N? The first one seems more logical.

+1 for the proposal, I see this as necessary for the rewrite.

[cmarcelo]

Thanks for the review. Yes, it is the first one. I see how the original description is ambiguous, I'll improve that on the command help message.

[cmarcelo]

@tmarcu @kevincwells could one of you take a look at this before I proceed with it? :-)

[kevincwells]

The overall idea makes sense to me -- +1 for obsoleting pack-maker.sh with mixer functionality.

As far as CLI, the meaning of --back -- and how it differs from --from -- definitely feels unclear at first. Maybe it could be named something a little more self-explanatory?

--back K means to build packs "for the previous K versions", and --back K --to N means "for the K versions leading up to N".... so maybe even something like --num-versions?

[cmarcelo]

OK! I was just reusing the name "back" from a previous PR. I'll incorporate one of those names instead.