Figure out how best to present overridden/default/custom data

Regarding #602938: Provide default styles in image.module (add hook_image_default_styles) → :
In #drupal, yoroy and Bojhan pointed out that this Default / Overridden / Custom business probably falls under "too much information" for the vast majority of site builders, who are not deploying code through something like SVN, though it is very handy for those who are. I'm on the fence about it, personally. I can see both sides.

As a site builder who *does* follow best practices, this information is really useful so I know which database-related thingies I haven't moved to code yet. Yet, core itself doesn't do anything with this information (there's no image style export functionality) and we also do not do show this type of information in other places in core. For example, with blocks, the way I know whether something is module-provided or custom is whether it has a "remove" link next to it. If so, I added it myself, and I need to move it to code. If not, it's already provided by a module. However, blocks don't have this interim "Overriden" step: they're either module-provided, or custom, and you're stuck with whatever the module gives you.

This issue is for discussing this a bit more, since the intention here is for core to establish a pattern that contrib can follow.