Significant sprite packing memory leak fixes

additional thanks to GlFolker for reporting issues with undisposed content icon pixmaps

core/src/mindustry/world/blocks/environment/Floor.java

@@ -177,6 +177,7 @@ public class Floor extends Block{
         }
 
         packer.add(PageType.environment, name + "-edge", result);
+        result.dispose();
     }
 
     @Override

core/src/mindustry/world/blocks/environment/OreBlock.java

@@ -69,6 +69,8 @@ public class OreBlock extends OverlayFloor{
                 packer.add(PageType.editor, "editor-block-" + name + "-full", image);
                 packer.add(PageType.main, "block-" + name + "-full", image);
             }
+
+            image.dispose();
         }
     }