Implemented persistency for delete/rename operations. Also set the user and group of all object files to the user/group of the root directory.
BUGFIX: Remove duplicate entries in FS directory listings.
Implemented support for symbolic links.
Changed implementation of blacklist to use SHA-1 directly instead of object reference.
Replaced use of object context with mode only and reimplemented delete/rename persistency based on SHA-1/mode.
Implemented directory pruning in blacklist when last child of a tree is removed.