Add no-delete-local to avoid remote->local delete synchronization.

Signed-off-by: Edward Z. Yang <ezyang@mit.edu>
Fast message moving using mv and COPY.

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

Signed-off-by: Edward Z. Yang <ezyang@mit.edu>
Don't make the file disappear, ever.

Signed-off-by: Edward Z. Yang <ezyang@mit.edu>
Nofast, sqlite is good.

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