v2.13.8: Fix QueryCache invalidation for exists() and selectBy(); add VCTrace#tryExtractCreationDate() tool; add prewarmIntervalJitter option; improve ToolScoreboard UI

v2.13.8: Fix QueryCache invalidation for exists() and selectBy(); add VCTrace#tryExtractCreationDate() tool; add prewarmIntervalJitter option; improve ToolScoreboard UI #72