Moves the file-comparison handlers out of main.cpp into their
own translation unit:
--diff-wcp --diff-zone
--diff-glb --diff-wom
--diff-wob --diff-whm
--diff-woc --diff-jsondbc
--diff-extract --diff-checksum
main.cpp drops 15,653 → 14,732 lines (-921). One build error
during extraction (missing #include for NpcSpawner /
ObjectPlacer / QuestEditor used by --diff-zone) caught by
build and fixed.
