Improve FreeJ2ME's standalone and libretro core save paths.

[AShiningRay]

Previously the RA core would save configs incorrectly, now the folders are better organized, and the code was altered in a way that doesn't cause problems for the standalone versions of FreeJ2ME. Refer to #138 for more info about this.

~~Edit: Don't merge yet, just found a bug on DOOM II RPG through the libretro frontend.~~

Edit 2: Alright, now it should be fine.