Separate out DOI build. (#718)

gamedata/core.games/master.games.txt

@@ -93,6 +93,7 @@
 	"engine.insurgency.txt"
 	{
 		"engine"	"insurgency"
+		"engine"	"doi" // #cheating #yolo
 	}
 	
 	"game.dinodday.txt"

gamedata/sdkhooks.games/master.games.txt

@@ -59,6 +59,7 @@
 	"engine.insurgency.txt"
 	{
 		"engine"	"insurgency"
+		"engine"	"doi" // #cheating #yolo
 	}
 	
 /*

gamedata/sdktools.games/master.games.txt

@@ -88,6 +88,7 @@
 	"engine.insurgency.txt"
 	{
 		"engine"	"insurgency"
+		"engine"	"doi" // #cheating #yolo
 	}
 	
 	"game.tf.txt"