[Spells] Added IsNightTime() for Dance of the Fireflies (#3667)

* Added IsNightOnly for Dance of the Fireflies spell which should only be cast at night from 7pm to 4pm.

* Update to include IsDayTime and replace magic numbers.

zone/spells.cpp

@@ -711,6 +711,18 @@ bool Mob::DoCastingChecksZoneRestrictions(bool check_on_casting, int32 spell_id)
 		Message(Chat::Red, "You cannot cast detrimental spells here.");
 		return false;
 	}
+	/*
+		Zones where you can not cast a spell that is for daytime or nighttime only
+	*/
+	if (spells[spell_id].time_of_day == SpellTimeRestrictions::Day && !zone->zone_time.IsDayTime()) {
+		MessageString(Chat::Red, CAST_DAYTIME);
+		return false;
+	}
+
+	if (spells[spell_id].time_of_day == SpellTimeRestrictions::Night && !zone->zone_time.IsNightTime()) {
+		MessageString(Chat::Red, CAST_NIGHTTIME);
+		return false;
+	}
 
 	if (check_on_casting) {
 		/*

zone/string_ids.h

@@ -63,6 +63,8 @@
 #define SAC_TOO_HIGH				204		//This being is too powerful to be a sacrifice.
 #define CANNOT_SAC_SELF				205		//You cannot sacrifice yourself.
 #define SILENCED_STRING				207		//You *CANNOT* cast spells, you have been silenced!
+#define CAST_DAYTIME                208		//Spell can only be cast during the day.
+#define CAST_NIGHTTIME              209		//Spell can only be cast during the night.
 #define CANNOT_AFFECT_PC			210		//That spell can not affect this target PC.
 #define SPELL_NEED_TAR				214		//You must first select a target for this spell!
 #define SUMMON_ONLY_GROUP_CORPSE	215		//You must first target a living group member whose corpse you wish to summon.