simplified some loops

These changes were done by running the following command:

    gofmt -s -w *.go

robot.go

@@ -311,7 +311,7 @@ func (r *Robot) Tick(g *game) {
 
 func (r *Robot) scan(g *game) {
 	r.Scanners = r.Scanners[:0]
-	for player, _ := range g.players {
+	for player := range g.players {
 		for _, bot := range player.Robots {
 			if bot.Id == r.Id || bot.Health <= 0 {
 				continue
@@ -327,7 +327,7 @@ func (r *Robot) scan(g *game) {
 		}
 	}
 
-	for proj, _ := range g.projectiles {
+	for proj := range g.projectiles {
 		if proj.Owner == r {
 			continue
 		}