Removed .. and . entries

No longer need to be stored on disk, can be simulated on
the chip side. As mentioned in other commits, the parent
entries had dozens of problems with atomic updates, as
well as making everything just a bit more complex than
is needed.

tests/test_orphan.sh

@@ -17,7 +17,7 @@ tests/test.py << TEST
 TEST
 # remove most recent file, this should be the update to the previous
 # linked-list entry and should orphan the child
-rm -v "blocks/$(ls -t blocks | sed -n '/^[0-9a-f]*$/p' | sed -n '1p')"
+rm -v blocks/8
 tests/test.py << TEST
     lfs_mount(&lfs, &config) => 0;
     lfs_stat(&lfs, "parent/orphan", &info) => LFS_ERROR_NO_ENTRY;