Add line tool and undo tools

core/src/io/anuke/mindustry/entities/Player.java

@@ -10,6 +10,8 @@ import io.anuke.mindustry.input.PlaceMode;
 import io.anuke.mindustry.resource.Mech;
 import io.anuke.mindustry.resource.Recipe;
 import io.anuke.mindustry.resource.Weapon;
+import io.anuke.mindustry.world.Tile;
+import io.anuke.mindustry.world.blocks.Blocks;
 import io.anuke.ucore.core.*;
 import io.anuke.ucore.entities.DestructibleEntity;
 import io.anuke.ucore.util.Angles;
@@ -74,6 +76,11 @@ public class Player extends DestructibleEntity{
 		
 		if(health < maxhealth && Timers.get(this, "regen", 50))
 			health ++;
+
+		Tile tile = world.tileWorld(x, y);
+		if(tile != null && tile.floor().liquid && tile.block() == Blocks.air){
+			damage(health+1); //drown
+		}
 		
 		vector.set(0, 0);
 		

core/src/io/anuke/mindustry/entities/TileEntity.java

@@ -54,18 +54,20 @@ public class TileEntity extends Entity{
 	}
 	
 	public void onDeath(){
-		dead = true;
 		
 		if(tile.block() == ProductionBlocks.core){
 			Vars.control.coreDestroyed();
 		}
-		
-		Block block = tile.block();
-		
-		block.onDestroyed(tile);
-		
-		Vars.world.removeBlock(tile);
-		remove();
+
+		if(!dead) {
+			dead = true;
+			Block block = tile.block();
+
+			block.onDestroyed(tile);
+
+			Vars.world.removeBlock(tile);
+			remove();
+		}
 	}
 	
 	public void collision(Bullet other){

core/src/io/anuke/mindustry/entities/enemies/Enemy.java

@@ -9,11 +9,14 @@ import io.anuke.mindustry.entities.*;
 import io.anuke.mindustry.graphics.Fx;
 import io.anuke.mindustry.graphics.Shaders;
 import io.anuke.mindustry.world.Tile;
+import io.anuke.mindustry.world.blocks.Blocks;
 import io.anuke.ucore.UCore;
 import io.anuke.ucore.core.*;
 import io.anuke.ucore.entities.*;
 import io.anuke.ucore.util.*;
 
+import static io.anuke.mindustry.Vars.world;
+
 public class Enemy extends DestructibleEntity{
 	public final static Color[] tierColors = { Color.valueOf("ffe451"), Color.valueOf("f48e20"), Color.valueOf("ff6757"), Color.valueOf("ff2d86") };
 	public final static int maxtier = 4;
@@ -211,6 +214,11 @@ public class Enemy extends DestructibleEntity{
 		}else{
 			idletime = 0;
 		}
+
+		Tile tile = world.tileWorld(x, y);
+		if(tile != null && tile.floor().liquid && tile.block() == Blocks.air){
+			damage(health+1); //drown
+		}
 		
 		if(Float.isNaN(angle)){
 			angle = 0;