Add setting for linkgraph times to be in non daylength scaled days.

Savegame format change for link graph jobs.
Change link graph scheduler to support more than one operation
per day, on _date_fract ticks other than SPAWN_JOIN_TICK.

src/linkgraph/linkgraphjob.cpp

@@ -28,6 +28,15 @@ INSTANTIATE_POOL_METHODS(LinkGraphJob)
  */
 /* static */ Path *Path::invalid_path = new Path(INVALID_NODE, true);
 
+static DateTicks GetLinkGraphJobJoinDateTicks()
+{
+	DateTicks ticks = _settings_game.linkgraph.recalc_time * DAY_TICKS;
+	if (_settings_game.linkgraph.recalc_not_scaled_by_daylength) {
+		ticks /= _settings_game.economy.day_length_factor;
+	}
+	return ticks + (_date * DAY_TICKS) + _date_fract;
+}
+
 /**
  * Create a link graph job from a link graph. The link graph will be copied so
  * that the calculations don't interfer with the normal operations on the
@@ -40,7 +49,8 @@ LinkGraphJob::LinkGraphJob(const LinkGraph &orig) :
 		link_graph(orig),
 		settings(_settings_game.linkgraph),
 		thread(NULL),
-		join_date(_date + _settings_game.linkgraph.recalc_time),
+		join_date_ticks(GetLinkGraphJobJoinDateTicks()),
+		start_date_ticks((_date * DAY_TICKS) + _date_fract),
 		job_completed(false)
 {
 }