Use actual image size instead of preset sizes for box art

[Epicpkmn11]

What's changed?

• This makes the box art use the actual size of the image its drawing instead of a preset for that type of rom
• Any size from 0x0 to 256x192 should work and bigger are ignored (though you don't really want to go larger than the user photo picture)
• Both cache and non-cache modes are working for me (DSi), however I can't test on flashcard

Where have you tested it?

DSi (K) with latest TWiLight & Unlaunch.

Video: (Spirit Tracks is 100x100, Heart Gold is 256x192, ホワイト is 258x192 (too big, so skipped))

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Pull Request status

• This PR has been tested using the provided devkitPro, devkitARM, and EasyGL2D.

[RocketRobz]

Any chance this can be implemented to quick menu as well?

[Epicpkmn11]

Oh yeah, I kinda forgot about that ;P
Just give me a sec, it should be easy

[Epicpkmn11]

Done!