Save state doesn't work correctly for games that make use of CHR RAM

[blahness]

Since you're not saving the carts chr data when it's written to games such as Metroid have a black screen on state load. This same issue would apply to games making use of PRG RAM.

[fogleman]

@blahness Thanks - not sure how I missed this! Fixed now in master. Unfortunately it breaks existing savefiles, which may need to be rm'd from the ~/.nes/save folder.

[blahness]

The INES header format states that if the CHR ROM size is 0 then it's CHR RAM. I think the best play is to mark the CHR data as RAM in that case & only save it in the state file if it's marked as RAM. Since your emulator in its current state doesn't allow PRG data to be written to there's no point in saving it right now. It's just something to keep in mind when it's supported.