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)
reduces loading time (don't have to allocate conversion arrays when
launching a gen7 game), and separates things to easier to manage
locations
reworks gen3 string encode/decode, no longer does 3->4->5 and 5->4->3;
instead goes straight to the end result without an intermediary format.
String sanitization should probably be broken up rather than reused, oh
well.
be explicit that the string is empty rather than possibly missing
disallow encrypted export for BK4 (they're not encrypted), removes type
check
simplify replaceall in showdownset (don't call ReplaceAll 4x, just get
valid chars and rebuild)
simplify get ribbon sprite name (precompute ToLower and appended values
