Remove some unnecessary properties from SaveFile
Enumerate checksum flag results for GC memcard checking
Remove unnecessary checks on savefile type
Add some documentation
Decapitalize some method parameters
GameInfo has been the storage for the current Game Language environment
When using GameInfo, only one environment is tracked at a time, which is
initialized by the PKM editor (items, moves). Rework things to allow
multiple filtered sources to exist, and keep the filtering logic in
PKHeX.Core for reuse in other programs... ;)
