1) properly disable alarm before exiting ForkCmd
   - this was causing SIGALRM to get sent when it shouldn't have, and
     probably caused the renewal failures.
   - was introduced accidentally yesterday when I unwittingly committed
     some beta libplab code along with the rootball version string fix.

2) Changed semantics of the renew daemon s.t. it only sends a single message
   for each invocation of the renewal loop - summarizes the ones that failed.

The rest of the code I committed accidentally yesterday seems to be working
just fine.  It all looks sane on perusal.