disposable UI; loading screen mockup (i heard like loading screen -- sonic 06)

src/net/torvald/terrarum/gameactors/ActorWithBody.kt

@@ -1,7 +1,6 @@
 package net.torvald.terrarum.gameactors
 
 import com.badlogic.gdx.graphics.g2d.SpriteBatch
-import com.badlogic.gdx.graphics.glutils.ShapeRenderer
 
 /**
  * Actor with visible body
@@ -13,4 +12,6 @@ abstract class ActorWithBody(renderOrder: RenderOrder) : Actor(renderOrder) {
     abstract fun drawBody(batch: SpriteBatch)
     abstract fun drawGlow(batch: SpriteBatch)
     open var tooltipText: String? = null // null: display nothing
+
+    abstract fun dispose()
 }

src/net/torvald/terrarum/gameactors/ActorWithPhysics.kt

@@ -1451,6 +1451,11 @@ open class ActorWithPhysics(renderOrder: RenderOrder, val immobileBody: Boolean
                 this + 2 * Math.PI
             else
                 this
+
+    override fun dispose() {
+        sprite?.dispose()
+        spriteGlow?.dispose()
+    }
 }
 
 inline fun Int.sqr(): Int = this * this