issue #26 resolved (someone is hoolding stale ingame context)

src/net/torvald/terrarum/worlddrawer/BlocksDrawerNew.kt

@@ -31,6 +31,7 @@ import kotlin.math.roundToInt
  */
 internal object BlocksDrawer {
 
+    /** World change is managed by IngameRenderer.setWorld() */
     internal var world: GameWorld = GameWorld.makeNullWorld()
 
     private val TILE_SIZE = CreateTileAtlas.TILE_SIZE
@@ -724,9 +725,7 @@ internal object BlocksDrawer {
 
     fun dispose() {
         printdbg(this, "dispose called by")
-        Thread.currentThread().stackTrace.forEach {
-            printdbg(this, "--> $it")
-        }
+        printStackTrace(this)
 
         weatherTerrains.forEach { it.dispose() }
         tilesWire.dispose()

src/net/torvald/terrarum/worlddrawer/FeaturesDrawer.kt

@@ -13,6 +13,8 @@ import net.torvald.terrarum.worlddrawer.CreateTileAtlas.TILE_SIZE
  * Created by minjaesong on 2015-12-31.
  */
 object FeaturesDrawer {
+
+    /** World change is managed by IngameRenderer.setWorld() */
     internal var world: GameWorld = GameWorld.makeNullWorld()
 
     //const val TILE_SIZE = CreateTileAtlas.TILE_SIZE

src/net/torvald/terrarum/worlddrawer/LightmapRendererNew.kt

@@ -38,6 +38,7 @@ import net.torvald.terrarum.realestate.LandUtil
 object LightmapRenderer {
     private const val TILE_SIZE = CreateTileAtlas.TILE_SIZE
 
+    /** World change is managed by IngameRenderer.setWorld() */
     private var world: GameWorld = GameWorld.makeNullWorld()
 
     private lateinit var lightCalcShader: ShaderProgram