Separate character.json for custom live2d

[DenkoStrike]

Considering all sub_ live2d are in the files, it can be assumed you plan on implementing them at some point. If not, hey there's another suggestion-

Though for now, people will either need to use a png or implement the live2d model themself. I'm still experimenting with the latter, up to the point of modifying character.json. It then occurred to me that updates to character.json could risk overwriting custom pointers. Would it be possible to implement a secondary character.json specifically for custom live2d so there's no risk of the pointers being overwritten?