Evaluate new background

[Mte90]

As it is a new release maybe a new background can be interesting.

[Mte90]

Looking at the code https://github.com/Mte90/GBAATM-Rebirth/blob/master/core/romfuncs.cpp#L432 the background is there in a specific index.

The best thing to do is to split this file in various and keep a compiled version just to speed up and avoid other code changes.

[Mte90]

With https://gist.github.com/Mte90/b074665a3fca87416cd11f409f111653 is possible to get as array a specific file but the original trainermenu.h includes also font and selection bar and maybe some code that during the generation get change for the input values.

[Mte90]

Using https://github.com/Mte90/GBAATM-Rebirth/releases/tag/bin2array it is possible to generate some files but the content is not the same of trainerint variable at all so I need to investigate.

[Mte90]

Maybe this tool https://github.com/LuckyLights/png2gb can help with that

[Mte90]

There are also tools for this here http://www.richwhitehouse.com/index.php?content=inc_projects.php&showcat=GBA

[Mte90]

Image converter for https://github.com/MrCheeseWasTaken/ImgToC