message: Turn on graphene by default.
  Fixes bug in where graphene was advertised as on via service bits, but wasn't actually turned on unless the user had '-use-grapheneblocks=1' in their config file/CLI args.
diff: @@ -1345,7 +1345,7 @@ bool HaveGrapheneNodes()
  return false;
  }
  -bool IsGrapheneBlockEnabled() { return GetBoolArg("-use-grapheneblocks", false); }
  +bool IsGrapheneBlockEnabled() { return GetBoolArg("-use-grapheneblocks", DEFAULT_USE_GRAPHENE_BLOCKS); }
  bool CanGrapheneBlockBeDownloaded(CNode *pto)
  {
  LOCK(pto->cs_mapgrapheneblocksinflight);
  