Increase abstraction for arbitrary slot get/set operations, and fracture
SAV4 behavior for each game type.
Adds: Undo/Redo of party slot changes
Fixes: Fixed Gen5 daycare slot 2 reading, and EXP reading
Fixes: Some slot color glitchiness
Fixed: Box layout editor now hides the flag label if no flags are
present
Fixed: Gen7 box flags are now shown (unknown purpose lol)
Changed: savefile objects are generally smaller (removed a few shared
offset fields)
A little bit cleaner when the logic is separated
Keep an abstraction of BoxEdit to cache the current box contents.
Already fetched to show sprites; any future fetches (for preview text /
hover sprite) can reuse the already fetched pkm data.
Should probably rewrite this stuff completely, but effort better spent
elsewhere
