don't resolve immutable folders and files multiple times
fixes duplicate DVD/playlist/feed entries:

	https://code.google.com/p/ps3mediaserver/issues/detail?id=566
	https://code.google.com/p/ps3mediaserver/issues/detail?id=636
	https://code.google.com/p/ps3mediaserver/issues/detail?id=1483

Conflicts:
	CHANGELOG.txt
	src/main/java/net/pms/dlna/ChapterFileTranscodeVirtualFolder.java
	src/main/java/net/pms/dlna/DLNAResource.java
	src/main/java/net/pms/dlna/DVDISOTitle.java
	src/main/java/net/pms/dlna/Feed.java
	src/main/java/net/pms/dlna/FileTranscodeVirtualFolder.java
	src/main/java/net/pms/dlna/PlaylistFolder.java