[hh_ht11xx] add new driver for keychain 55 in 1

[Figur8]

also some code clean up

[felipesanches]

I'd like to inform that this is the first PR of Ismael (@Figur8), one of the 3 people I am offering some mentoring on MAME development.

The content of this PR was authored by both of us, as we've prepared it on a video call conversation in which I explained to him many aspects of how the code is organized. I hope I can help his journey into MAME development to be smoother, by offering that kind of support.

Having said that, there are a few aspects of this PR that may be a bit controversial, so I'd like to get feedback on how to do it properly.

There are a few input names that are now in all caps because that's how they're depicted (as silkscreen labels) on the handheld.
We were a bit unsure about that, but we considered it reasonable to describe it that way. I am not sure if MAME has a specific policy about how to handle that. If needed, we can change them back to lowercase.

Also, the input port names were very confusing with names IN1, IN2 and IN3 while being addressed as m_in[0], m_in[1] and m_in[2] and in reality being called PP, PM and PS. So we believe the refactored implementation is easier to read, specially when cross-referencing with other info about the hardware that we could find online (such as https://github.com/azya52/BrickEmuPy/blob/main/assets/Keychain55in1.brick).

You can count on both me and @Figur8 to swiftly address any other issues in this PR, as we'd like to help Ismael to become a regular contributor to MAME.

[felipesanches]

Here's a photo of the real device:

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And at https://github.com/azya52/BrickEmuPy/blob/main/assets/Keychain55in1.svg there's an SVG that could in the future help us in preparing a .lay file for this handheld:

[ajrhacker]

Yes, I would prefer that the buttons be named in mixed case.

Who should this new system be specifically credited to?

[felipesanches]

Yes, I would prefer that the buttons be named in mixed case.

@Figur8, please follow @ajrhacker's suggestion of reverting the button names to mixed case.

Who should this new system be specifically credited to?

This PR is a collaboration between Figur8 and myself, so you can credit it to both of us.

[Figur8]

Yes, I would prefer that the buttons be named in mixed case.

Who should this new system be specifically credited to?

Resolved!

[felipesanches]

Thanks, @Figur8!

[ajrhacker]

It looks as if the actual name of this handheld is "Pikorin 55" (ピコリン55), made by Gametech.

https://jp.mercari.com/item/m30878850270?srsltid=AfmBOoq3MWfiy9CXS2fMxhBFiyrUTOhGqjuwcmtabHW9ofdtyNLrxyP6

[felipesanches]

It looks as if the actual name of this handheld is "Pikorin 55" (ピコリン55), made by Gametech.

https://jp.mercari.com/item/m30878850270?srsltid=AfmBOoq3MWfiy9CXS2fMxhBFiyrUTOhGqjuwcmtabHW9ofdtyNLrxyP6

Thanks! Can you quickly add that correct name and merge?

I'd like to help @Figur8 on his next steps to add more similar games to this driver.

[ajrhacker]

There's a similar-looking "Pikorin Bros." (ピコリンブロス) that might be worth investigating by whoever is dumping handhelds like this:

https://jp.mercari.com/item/m68242718940?srsltid=AfmBOop2ENOStGPW6V1QnrvJxiue6nTrjr9le11CHHcso5threLOpOEy

[felipesanches]

Thanks, @ajrhacker!

Congrats on your first PR merged on MAME, @Figur8!