instead of osgDB::Registry where it original lay. This has been done to allow
fileName strings to be encode data rather than just file names, such as one
requires when using PagedLOD along with plugins for doing dynamic tesselation.
storage of the path lists into osgDB::Registry, and changed the data
structor from a char* to a std::deque. Changed a names of couple of the
convinience functions in osgDB/FileUtils to better reflect the two
public FilePathList's - DataFilePathList and the LibraryFilePathList.
Added support into the osgDB::Registry::readNode/Image/Object methods
for pushing and popping the path of the current file being loaded.
