SWSYNC: Don't prepare DB transaction unless needed:

Before:

  symbolicweb.core> (time (dotimes [i 100] (swsync)))
  "Elapsed time: 4304.112775 msecs"

..after:

  symbolicweb.core> (time (dotimes [i 100] (swsync)))
  "Elapsed time: 34.71885 msecs"
Switch to a "global" SWSYNC.
START-SERVER: Minor adjustments.