Put current map and entrance into Data Storage

[Brian0255]

PR for #57

Initially I thought just the map ID would be enough, but it seems like the entrance that gets used on transitions is also needed for some very messy dungeon layouts, where different floors will use the same map ID

I did also change IN_GAME to MAP_ID since that's what it seems to actually be, but let me know if you'd like that changed, along with anything else

Might want to wait on this a bit until I can verify entrance ID is enough? I figured this is a good proof of concept though

[Brian0255]

Tested this out with the PopTracker pack and it seems to be working well using just the map and entrance ID, so I figure this is ready for review now

[Dragion147]

I think this looks ok, @cjmang any opinions on your end? same ingame check is used (different name) and otherwise its another byte that is being read and a flag being set in datastorage if i see this correctly

[cjmang]

Overall seems fine. The only concern I have is I don't think this will work very well for same slot co-op. I don't mind merging this in as is, but it would be nice to handle this case.