Added Radar tech and Fighter unit

Credits.md

@@ -390,7 +390,8 @@ All the following are from [the Noun Project](https://thenounproject.com) licenc
 
 ### Information
 * [Pill](https://thenounproject.com/term/pill/780458/) By Alex Arseneau for Pharmaceuticals
-* [Computer](https://thenounproject.com/term/computer/1967529/) By Shastry
+* [Computer](https://thenounproject.com/term/computer/1967529/) By Shastry for Computers
+* [Satellite Dish](https://thenounproject.com/search/?q=satellite%20dish&i=2054441) By Vectors Market for Radar
 * [Nuclear Reactor](https://thenounproject.com/term/nuclear-reactor/426463/) By Jeremie Sommet for Nuclear Fission 
 * [Ecology](https://thenounproject.com/term/ecology/1970666/) By ProSymbols
 * [Robotic Arm](https://thenounproject.com/term/robotic-arm/1970874/) By Karl Gilbert for Robotics

android/assets/jsons/Techs.json

@@ -437,6 +437,11 @@
 				prerequisites:["Electronics"],
 				uniques:["+10% science and production in all cities"]
 			},
+			{
+				name:"Radar",
+				row:6,
+				prerequisites:["Ballistics","Electronics"]
+			},
 			{
 				name:"Combined Arms",
 				row:7,
@@ -469,7 +474,7 @@
 			{
 				name:"Rocketry",
 				row:6,
-				prerequisites:["Combined Arms","Computers"]
+				prerequisites:["Combined Arms","Radar"]
 			}
 		]
 	},

android/assets/jsons/Units.json

@@ -848,6 +848,8 @@
 		cost: 325,
 		requiredTech:"Flight",
 		requiredResource:"Oil",
+		upgradesTo:"Fighter",
+		obsoleteTech:"Radar",
 		hurryCostModifier:20,
 		uniques:["[50]% chance to intercept air attacks","Bonus vs Bomber 150%",
 			"6 tiles in every direction always visible"]
@@ -942,6 +944,21 @@
 	
 	// Modern era
 	
+	{
+		name:"Fighter",
+		unitType:"Fighter",
+		movement:1,
+		strength:35,
+		rangedStrength:45,
+		range:8,
+		cost: 375,
+		requiredTech:"Radar",
+		requiredResource:"Oil",
+		hurryCostModifier:20,
+		uniques:["[100]% chance to intercept air attacks","Bonus vs Bomber 150%",
+			"6 tiles in every direction always visible"]
+		attackSound:"shot"
+	},
 	{
 		name:"Landship",
 		unitType:"Armor",