gfx_SetCharData is broken #221
Description
I'm no ASM expert, but I did some debugging in CEmu and it looks like DE and HL are backwards by the time we make it to this LDIR, and I'm guessing this RET Z is meant to return if the uint8_t *data passed to gfx_SetCharData() is NULL, but I found that it always executes, even if uint8_t *data isn't NULL.
Looking at git blame, I don't know how no one noticed this was broken for 2 whole years, but I keep finding broken routines that no one uses :3