Revised rootDirs search order

rootDir comes after langDir and userDir; NIFile defaults to the
last list entry
Undo "Solved problem with duplicate folder names in multiple root folders"

This partly reverts commit 64c1ee1ee143f27b5176c2acf7034f54dc38bec5.

Reverted due to undesirable side-effects.
Merge branch 'devel' into devel-ci

Conflicts:
	src/infinity/util/NIFile.java