Rename Borders to Decoration Set

[Lazorne]

[XargonWan]

We should make sure that we really want this change, it's not complicated as it's almost a clever find and replace, however please consider:

• RetroArch refers to borders in many files, even its default directory is overlays/borders
• retrodeck/borders will change in retrodeck/bezels, so we should add a post update script to rename that folder if found o 0.7.5b+

Do we really know about the real difference between borders and bezels?

[Lazorne]

Decoration Set Niroku:

Borders, bezels, decorations, overlays. They have all been used interchangeably. The main reason batocera uses "decoration set" is to distinct itself from this. Not even retroarch refers to the term consistently.

So if Decoration Set is good enough for Batocera as the collective term for: Borders, bezels, decorations, overlays. I think we can just use it as well then explain on the wiki and in the Configurator add use the words: Borders, bezels, decorations, overlays so people can find it no matter how they search for it .

Then we can just make it a standard term for the whole thing and standardize the language.

Decoration Set is the collective term for: Borders, bezels, decorations, overlays.

[XargonWan]

For the moment we actually have only borders, when we will expand into shaders and stuff we can change the naming.