[z2034] Don't check registry for game folder on windows, use relative "Data" dir, similar to linux.

Fixes annoyance when you have multiple wow clients and building vmaps fails for reason that extractor takes path from wrong client even though it is located inside the correct directory

Signed-off-by: stfx <stfx@hotmail.de>

(based on commit 6518789)

Signed-off-by: Nighoo <nighoo@overninethousand.de>

(based on commit [s1646] - 51aac0f)