Konami identifiers and IIDX products

[voidderef]

Quite the "big bang" PR that adds too many things at once. However, this allowed me to iterate on the various ideas/concepts we came up regarding the product identifiers, its format and how they are used by Konami.

• Bootstrap "Konami product identifiers" with a list of products gather from various sources
• Add various products with descriptions, mainly focused on IIDX
• Add IO boards used on IIDX
• Bootstrap dongle type docs
• Bootstrap software docs, focus IIDX

I hope this rather huge changeset provides a decent foundation to extend upon easily. There is still some personal knowledge that is not included, but I am hoping that I will add this later (if someone else hasn't done it instead).

[voidderef]

Great work so far, thanks a lot! I've addressed some things with regard to organisation and minor changes, but the big lines look good. I'm really starting to think we need a graph DB...

Thanks. I haven't looked into solutions using markdown files as a basis, but I know there are some out there allowing you to present these with extended search functionalities based on some custom index. As you can still use plain text search with this right now and if we keep cross-referencing stuff in a meaningful way, I think the current markdown based solution is good enough and especially easy to handle and contribute to.

[voidderef]

Updated PR description and force pushed my "final changeset". I still have to re-write the history and turn the WIP commits into best effort chunks to avoid a single huge big bang in the history. Let's give this the finishing touches regarding feedback and fixes first.