Fix up pinned logic

Signed-off-by: Edward Z. Yang <ezyang@mit.edu>
Only pay for block_record on sanity checking

Signed-off-by: Edward Z. Yang <ezyang@mit.edu>
Short-cut clearNursery.

Signed-off-by: Edward Z. Yang <ezyang@mit.edu>
[DIDN'T HELP!!!] Short-circuit round if no new static

Signed-off-by: Edward Z. Yang <ezyang@mit.edu>
[HACK] disable stats department

Signed-off-by: Edward Z. Yang <ezyang@mit.edu>
Refactor scav code

Signed-off-by: Edward Z. Yang <ezyang@mit.edu>
Recentralize some accounting structures.

Signed-off-by: Edward Z. Yang <ezyang@mit.edu>
Fastpath using parent pointers.

Signed-off-by: Edward Z. Yang <ezyang@mit.edu>