Add support for progressive/interlaced images

Here is a patch that adds a "progressive" option for jpegtran and an "interlace" option for optipng.

Also notice that I had to rework how the internal tools variables are stored in order to make the field grouping on the settings page make sense. Hopefully, this will also allow for additional settings for each internal tool in the future.

Updating the title as well to include reference to interlacing.

I test and it looks cool. The interface is well. And I got the jpeg images converted to progressive.

Before this patch, results of " google page insights" or "gtmetrix" (both webservices) where 80% of my images not progressive-compressed. After this patch, I have 100% of my images progressive-compressed :-)

Anyway, I would wait for some confirmations more before change status as reviewed&tested by the community.

Thanks.

With all the latest work I've been doing (cleanup/modularize/UI improvements) I've also implemented a binaries advanced settings functionality (locally), which will combine parts of this patch.

Should have something committed today.

Implementation committed along side #876482: UI overhaul