Fixed some Android bugs

core/src/io/anuke/mindustry/Vars.java

@@ -21,7 +21,8 @@ public class Vars{
 	//not marked as final, because of warnings
 	public static boolean debug = false;
 	
-	public static final int multiplier = android ? 2 : 1;
+	//turret and enemy shoot speed inverse multiplier
+	public static final int multiplier = android ? 3 : 1;
 	
 	public static final int tilesize = 8;
 	

core/src/io/anuke/mindustry/World.java

@@ -155,7 +155,9 @@ public class World{
 				return false;
 			}
 		}
-		return tile(x, y).block() == Blocks.air;
+		Tile tile = tile(x, y);
+		
+		return tile != null && tile.block() == Blocks.air;
 	}
 	
 	public static boolean cursorNear(){

core/src/io/anuke/mindustry/input/AndroidInput.java

@@ -119,6 +119,9 @@ public class AndroidInput extends InputAdapter{
 			lmousex = Gdx.input.getX(0);
 			lmousey = Gdx.input.getY(0);
 			player.breaktime = 0;
+			
+			mousex = Mathf.clamp(mousex, 0, Gdx.graphics.getWidth());
+			mousey = Mathf.clamp(mousey, 0, Gdx.graphics.getHeight());
 		}
 	}