dsynth - Get skips working, etc

dsynth - Get skips working, etc

* Get 'Skipped' working, and print a nice depdency chain for the reason
  why a packge got skipped.

* Added swap% to the dynamic worker reduction algorithm.  It startsr at
  10% swap used and maxes out at a 75% reduction with 40% of swap used.

* Add a slow-start feature so dsynth does not try to load all workers
  at startup simultaneously.  This gives the swap% and loadavg worker
  reduction code a chance to activate before the system becomes totally
  smashed.

* Cache the 0*.log logfile descirptors instead of open/write/close.